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1. Align the center of the protractor with the angle’s vertex.
The angle measure is 70 .° So, the angle is acute.
2. Align the center of the protractor with the angle’s vertex.
The angle measure is 90 .° So, the angle is a right angle.
3. Align the center of the protractor with the angle’s vertex.
The angle measure is 115 .° So, the angle is obtuse.
4. Draw a ray. Place the center of the protractor on the endpoint of the ray and align the protractor so the ray passes through the 0° mark. Make a mark at 55 .° Then draw a ray from the endpoint at the center of the protractor through the mark at 55 .°
5. Draw a ray. Place the center of the protractor on the endpoint of the ray and align the protractor so the ray passes through the 0° mark. Make a mark at 160 .° Then draw a ray from the endpoint at the center of the protractor through the mark at 160 .°
6. Draw a ray. Place the center of the protractor on the endpoint of the ray and align the protractor so the ray passes through the 0° mark. Make a mark at 85 .° Then draw a ray from the endpoint at the center of the protractor through the mark at 85 .°
7. Draw a ray. Place the center of the protractor on the endpoint of the ray and align the protractor so the ray passes through the 0° mark. Make a mark at 180 .° Then draw a ray from the endpoint at the center of the protractor through the mark at 180 .°
The measure of 1∠ is equal to the measure of 3.∠ The measure of 2∠ is equal to the measure of 4.∠
4. Four angles are formed with four pairs of adjacent angles. All four angle measures are equal when one of the angle measures is 90°. In the other cases, the nonadjacent angles have equal measures.
5. Sample answer:
7.1 On Your Own (pp. 272–273)
1. Sample answer:
adjacent: and ,XWY ZWY∠ ∠ and XWY XWV∠ ∠
vertical: and ,VWX YWZ∠ ∠ and YWX VWZ∠ ∠
2. Sample answer:
adjacent: and ,LJM LJK∠ ∠ and LJM NJM∠ ∠
vertical: and ,KJL PJN∠ ∠ and PJQ MJL∠ ∠
3. The angles are adjacent angles. The angles make up a straight angle, so the sum of their measures is 180 .°
85 180
95
x
x
+ ==
So, x is 95.
4. The angles are vertical angles. Because vertical angles are congruent, the angles have the same measure. So, x is 90.
5. The angles are adjacent angles. Because the angles make up a right angle, the sum of their measures is 90 .°
( )2 1 69 90
2 68 90
2 22
11
x
x
x
x
− + =
+ ===
So, x is 11.
6.
7.1 Exercises (pp. 274–275)
Vocabulary and Concept Check
1. 2 pairs; 4 pairs
2. 1 and 3;∠ ∠ 2 and 4;∠ ∠
Two angles are vertical angles when they are opposite angles formed by the intersection of two lines. Vertical angles are congruent angles.
Practice and Problem Solving
3.
4. and ABE CBD∠ ∠
5. Sample answer:
adjacent: and ;FGH HGJ∠ ∠ and HGJ JGK∠ ∠
vertical: and ;FGH JGK∠ ∠ and FGK JGH∠ ∠
6. Sample answer:
adjacent: and ;LMN NMP∠ ∠ and PMQ QMR∠ ∠
vertical: and ;LMN QMR∠ ∠ and SMR PMN∠ ∠
7. The angles listed are adjacent angles. A pair of vertical angles is and .ACB ECF∠ ∠
8. The angles are adjacent angles. Because the angles make up a right angle, the sum of their measures is 90 .°
35 90
55
x
x
+ ==
So, x is 55.
9. The angles are vertical angles. Because vertical angles are congruent, the angles have the same measure. So, x is 128.
10. The angles are adjacent angles. Because the angles make up a straight angle, the sum of their measures is 180 .°
11. The angles are vertical angles. Because vertical angles are congruent, the angles have the same measure.
4 25 75
4 100
25
x
x
x
− ===
So, x is 25.
12. The angles are adjacent angles. Because the angles make up a right angle, the sum of their measures is 90 .°
4 2 90
6 90
15
x x
x
x
+ ===
So, x is 15.
13. The angles are adjacent angles. Because the angles make up a straight angle, the sum of their measures is 180 .°
( )7 20 180
8 20 180
8 160
20
x x
x
x
x
+ + =
+ ===
So, x is 20.
14.
15.
16.
17.
18. The angles are vertical angles. Because vertical angles are congruent, the angles have the same measure.
2 41 127
2 86
43
x
x
x
+ ===
So, x is 43.
19. a. Sample answer:
b. Sample answer:
c. Sample answer:
20. Sample answer: One procedure is to draw one angle with its given measurement and then draw the second angle adjacent to it. A second procedure is to draw an angle whose measure is the sum of the two given angles. Then draw one of the angles inside that angle, sharing one of the sides. The other angle formed is the second given angle.
21. never; 1 and 3∠ ∠ are vertical angles and will always be congruent.
22. always; 1 and 4∠ ∠ are adjacent angles that form a straight angle, and the sum of their angle measures will always be 180 .°
23. sometimes; 2 and 3∠ ∠ are adjacent angles that form a straight angle, and the sum of their angle measures will always be 180 .° They will be congruent only when they each have an angle measure of 90°.
24. always; 1 and 2∠ ∠ are adjacent angles that form a straight angle, and the sum of their angle measures will always be 180 .° 3 and 4∠ ∠ are also adjacent angles that form a straight angle, and the sum of their angle measures will also always be 180 .°
25.
26. no; The ladder makes a 60° angle with the ground. Assuming that the angle between the ground and the wall is 90°, and knowing that the sum of the angles of a triangle add to 180°, the ladder makes a 30° angle with the wall.
b. When the sum of their angle measures is 90°. c.
d. When the sum of their angle measures is 180°. 2. a. If x and y are complementary angles, then both x and
y are always acute.
b. If x and y are supplementary angles, then x is sometimes acute.
c. If x is a right angle, then x is never acute.
d. If x and y are complementary angles, then x and y are sometimes adjacent.
e. If x and y are supplementary angles, then x and y are sometimes vertical.
3. a. supplementary; The angles are 60° and 120°. b. complementary; The angles are 45° and 45°.
c. neither; The angles are 180° and 90°.
d. supplementary; The angles are 90° and 90°.
4. a. Sample answers:
complementary: 1 and 2,∠ ∠ 3 and 4,∠ ∠
5 and 6,∠ ∠ and 7 and 8∠ ∠
supplementary: 9 and 10,∠ ∠ 10 and 11,∠ ∠
11 and 12,∠ ∠ and 9 and 12∠ ∠
b. 9 and 11,∠ ∠ 10 and 12∠ ∠
5. Two angles are complementary when the sum of their measures is 90 .° Two angles are supplementary when the sum of their measures is 180 .° Sample answer: 32° and 58° are complementary angles and 25° and 155° are supplementary angles.
7.2 On Your Own (pp. 278–279)
1. Because 26 64 90 ,° + ° = ° the angles are
complementary.
2. Because 44 136 180 ,° + ° = ° the angles are
supplementary.
3. Because 70 19 89 ,° + ° = ° the angles are neither
complementary nor supplementary.
4. The two angles make up a straight angle. So, the angles are supplementary, and the sum of their measures is 180 .°
( )4 5 41 180
4 46 180
4 134
33.5
x
x
x
x
+ + =
+ ===
So, x is 33.5.
5. The angles make up a right angle. So, the angles are complementary angles, and the sum of their measures is 90°.
( )2 3 90
3 3 90
3 93
31
x x
x
x
x
+ − =
− ===
So, x is 31.
6.
7.2 Exercises (pp. 280–281)
Vocabulary and Concept Check
1. Two angles are complementary when the sum of their measures is 90 .° Two angles are supplementary when the sum of their measures is 180 .°
21. Sample answer: One procedure is to draw one angle, then draw the other using a side of the first angle. Another procedure is to draw a right angle, then draw one of the angles inside the right angle, sharing one of the sides.
22. Sample answer: 100° is the measure of an angle that can be supplementary, but not complementary. Because complementary angles are less than 90 ,° any angle
that is greater than 90° and less than 180° cannot be complementary. So, an obtuse angle can be a supplementary angle but cannot be a complementary angle.
23. a. The two angles make up a straight angle. So, the angles are supplementary, and the sum of their measures is 180 .°
Let be the measure of .x CBD∠
6.2 180
7.2 180
25
x x
x
x
+ ===
So, the measure of CBD∠ is 25°.
b. Angles and EBD CBD∠ ∠ make up a right angle. So, the angles are complementary, and the sum of their measures is 90 .°
Let be the measure of .y EBD∠
25 90
65
y
y
+ ==
So, the measure of EBD∠ is 65°. Because FBE∠ and EBD∠ are congruent, the measure of FBE∠ is 65°.
24. yes; Sample answer 1: LMQ∠ is a straight angle. By
removing ,NMP∠ the remaining two angles
( ) and LMN PMQ∠ ∠ have a sum of 90°.
Sample answer 2: SML∠ and LMN∠ are complementary angles. SML∠ and PMQ∠ are vertical
angles and have the same measure (congruent). So, LMN∠ and PMQ∠ are also complementary.
25. Let 3x represent the measure of the larger angle and 2x represent the measure of the smaller angle. Because the angles are complementary, the sum of their measures is 90 .°
3 2 90
5 90
18
x x
x
x
+ ===
So, the measure of the larger angle is ( )3 3 18 54 .x = = °
26. Because vertical angles are congruent, the angles have the same measure. So, let x represent the measure of one complementary angle.
90
2 90
45
x x
x
x
+ ===
So, the measures of two vertical angles that are complementary angles are 45 .°
Let y represent the measure of one supplementary angle.
180
2 180
90
y y
y
y
+ ===
So, the measures of two vertical angles that are supplementary angles are 90 .°
27. Because the angles with measures 7x° and 20° are supplementary to the right angle, the sum of all three measures is 180 .°
7 90 20 180
7 110 180
7 70
10
x
x
x
x
+ + =+ =
==
Because the angle with the sum of the angle measures 5x° and 2y° is a vertical angle to the right angle, the sum
of their measures is 90 .° Substitute 10 for x and solve for y.
5. Knowing the side lengths or angle measures, you can use different colored straws, a ruler and protractor, or geometry software to see if the triangle is possible to construct.
6. Sample answers:
Side lengths in Activity 2a:
Side lengths in Activity 2b:
Side lengths in Activity 2c:
Side lengths in Activity 2d:
The sum of any two side lengths of a triangle must be greater than the remaining side length.
7. Angle measures for each triangle formed in Activity 3:
The sum of the angles of a triangle is 180°.
7.3 On Your Own (pp. 284–285)
1. The triangle has a right angle and two congruent sides. So, the triangle is a right isosceles triangle.
2. The triangle has all congruent angles and all congruent sides. So, the triangle is an equiangular and equilateral triangle.
3. Sample answer:
The triangle has two congruent angles and one right angle. So, it is a right isosceles triangle.
4. Sample answer:
The triangle has no congruent angles and one right angle. So, it is a right scalene triangle.
7.3 Exercises (pp. 286–287)
Vocabulary and Concept Check
1. Triangles can be classified by the size of their angles and by the number of congruent angles. An acute triangle has all acute angles. An obtuse triangle has 1 obtuse angle. A right triangle has 1 right angle. An equiangular triangle has 3 congruent angles.
Triangles can also be classified by the number of congruent sides they have. Scalene triangles have no congruent sides. Isosceles triangles have at least 2 congruent sides. Equilateral triangles have 3 congruent sides.
2. “Construct a triangle with no congruent sides” is different; Constructed triangle that is equilateral, equiangular and with 3 congruent sides:
6. The triangle has two are congruent sides and one right angle. So, the triangle is a right isosceles triangle.
7. The triangle has all congruent sides and all congruent angles. So, the triangle is an equilateral and equiangular triangle.
8. The triangle has two congruent sides and one obtuse angle. So, it is an obtuse isosceles triangle.
9. The triangle has no congruent sides and a right angle. So, it is a right scalene triangle.
10. The triangle has no congruent sides and all acute angles. So, it is an acute scalene triangle.
11. The triangle has no congruent sides and one obtuse angle. So, it is an obtuse scalene triangle.
12. The solution incorrectly concludes that a triangle is acute if it has some acute angles. Because 98 90 ,° > ° this
angle is obtuse. The triangle is an obtuse scalene triangle because it has one obtuse angle and no congruent sides.
13. The triangle has two congruent sides and all acute angles. So, it is an acute isosceles triangle.
14. Sample answer:
The triangle has no congruent sides and one right angle. So, it is a right scalene triangle.
15. Sample answer:
The triangle has no congruent sides and one obtuse angle. So, it is an obtuse scalene triangle.
16. Sample answer:
The triangle has two congruent sides and one obtuse angle. So, it is an obtuse isosceles triangle.
17. Sample answer:
18. Sample answer:
19. Sample answer:
20. Sample answer: Your friend is not correct because without any more information about the lengths of the sides or other angles, you could be constructing a right triangle or an obtuse triangle.
21. no; The sum of the angle measures of a triangle must be 180 .° Because 50 70 100 220,+ + = no triangle can
be constructed.
22. many; You can change the length of the second side used to create the 60° angle to construct many triangles.
23. many; You can change the angle formed by the two given sides to construct many triangles.
24. one; Only one line segment can be drawn between the end points of the two given sides.
25. no; The sum of any two side lengths must be greater than the remaining length. Because the two 2-inch sides have a sum less than 5, no triangle can be constructed.
The value of x is 67.5. The triangle has two congruent sides and all acute angles. So, the triangle is an acute isosceles triangle.
12. 60 180
2 60 180
2 120
60
x x
x
x
x
+ + =+ =
==
The value of x is 60. All three sides are congruent and all three angles are congruent. So, the triangle is an equilateral and equiangular triangle.
13. 132 180
2 132 180
2 48
24
x x
x
x
x
+ + =+ =
==
The value of x is 24. The triangle has two congruent sides and one obtuse angle. So, the triangle is an obtuse isosceles triangle.
14. ( )2 15 90 180
3 105 180
3 75
25
x x
x
x
x
+ + + =
+ ===
The value of x is 25 and the value of 2 15 2(25) 15 65x + = + = . The triangle has no
congruent sides and one right angle. So, the triangle is a right scalene triangle.
15. ( ) ( )10 3 5 180
5 5 180
5 175
35
x x x
x
x
x
+ + − + =
+ ===
The value of x is 35, the value of 10 35 10 45,x + = + = and the value of
( )3 5 3 35 5 100.x − = − = The triangle has no
congruent sides and one obtuse angle. So, the triangle is an obtuse scalene triangle.
16. If a triangle had two obtuse angles, then the sum of the angle measures would be greater than 180 .° So, a triangle can have at most one obtuse angle, and at least two acute angles.
17. a. 36 180
2 36 180
2 144
72
x x
x
x
x
+ + =+ =
==
The value of x is 72.
b. Because the length of each card is the same, the triangle formed must remain an isosceles triangle. So, the cards can be stacked such that the base of the triangle is shorter when the value of x is greater than 72, and longer when the value of x is less than 72. If
60,x = then the three cards form an equilateral
triangle. This is not possible because the two upright cards would have to be exactly on the edges of the base card. So, x must be greater than 60. If 90,x =then the two upright cards would be vertical, which is not possible. The card structure would not be stable. So, x must be less than 90. This means that the value of x is limited to 60 90.x< <
Study Help Available at BigIdeasMath.com.
Quiz 7.1–7.3 1. Sample answer:
adjacent: and ;PQR RQS∠ ∠ and RQS SQT∠ ∠
vertical: and ;PQR SQT∠ ∠ and PQT SQR∠ ∠
2. Sample answer:
adjacent: and ;YUZ ZUV∠ ∠ and ZUV VUW∠ ∠
vertical: and ;YUX WUV∠ ∠ and XUW YUV∠ ∠
3. The angles are adjacent angles. Because the angles are supplementary, the sum of their measures is 180 .°
4. The angles are adjacent angles. Because the angles are complementary, the sum of their measures is 90 .°
74 90
16
x
x
+ ==
So, x is 16.
5. The angles are vertical angles. Because vertical angles are congruent, the angles have the same measure.
10 59
49
x
x
+ ==
So, x is 49.
6. The two angles make up a straight angle. So, the angles are supplementary, and their sum is 180°.
( )2 5 75 180
2 80 180
2 100
50
x
x
x
x
+ + =
+ ===
So, x is 50.
7. The two make up a right angle. So, the angles are complementary, and their sum is 90°.
( )3 6 90
4 6 90
4 96
24
x x
x
x
x
+ − =
− ===
So, x is 24.
8.
9.
10.
11. 25 40 180
65 180
115
x
x
x
+ + =+ =
=
The value of x is 115. The triangle has one obtuse angle and no congruent sides. So, the triangle is an obtuse scalene triangle.
12. 90 180
2 90 180
2 90
45
x x
x
x
x
+ + =+ =
==
The value of x is 45. The triangle has a right angle and two angles are congruent. So, the triangle is a right isosceles triangle.
13. ( )20 60 60 180
20 120 180
100 180
80
x
x
x
x
− + + =
− + =+ =
=
The value of x is 80 and the value of 20 80 20 60.x − = − = The triangle has all congruent
angles and all congruent sides. So, the triangle is an equilateral and equiangular triangle.
14. One way is to use vertical angles to find that the measure of 2 is 115 .∠ ° Another way is to use supplementary angles to find that the measure of 3 is 65 .∠ ° Then use supplementary angles to find that the measure of
The sum of the angles of a quadrilateral is equal to 360°.
6. You can classify quadrilaterals using the properties of their sides and angles. A quadrilateral with exactly one pair of parallel sides is a trapezoid. A quadrilateral with two pairs of congruent adjacent sides and opposite sides that are not congruent is a kite. A quadrilateral with opposite sides that are parallel and congruent is a parallelogram. A parallelogram with four right angles is a rectangle, and a parallelogram with four congruent sides is a rhombus. A parallelogram that has both is a square.
7.4 On Your Own (pp. 294–295)
1. The quadrilateral has four congruent sides. So, it is a rhombus.
2. The quadrilateral has exactly one pair of parallel sides. So, it is a trapezoid.
3. The quadrilateral has four right angles. So, it is a rectangle.
4. 80 100 100 360
280 360
80
x
x
x
+ + + =+ =
=
The value of x is 80.
5. 81 90 124 360
295 360
65
x
x
x
+ + + =+ =
=
The value of x is 65.
6.
7.4 Exercises (pp. 296–297)
Vocabulary and Concept Check
1. All of the statements are true.
2. Two quadrilaterals with four right angles are a rectangle and a square.
3. Kite does not belong. It is the only type of quadrilateral listed that does not have opposite sides that are parallel and congruent.
Practice and Problem Solving
4. The quadrilateral has four congruent sides and four right angles. So, it is a square.
5. The quadrilateral has exactly one pair of parallel sides. So, it is a trapezoid.
6. The quadrilateral has four congruent sides. So, it is a rhombus.
7. The quadrilateral has two pairs of congruent adjacent sides and opposite sides that are not congruent. So, it is a kite.
8. The quadrilateral has opposite sides that are parallel and congruent. So, it is a parallelogram.
9. The quadrilateral has four right angles. So, it is a rectangle.
10. 65 115 115 360
295 360
65
x
x
x
+ + + =+ =
=
The value of x is 65.
11. 40 82 128 360
250 360
110
x
x
x
+ + + =+ =
=
The value of x is 110.
12. 52 90 90 360
232 360
128
x
x
x
+ + + =+ =
=
The value of x is 128.
13. 90 90 122 360
302 360
58
x
x
x
+ + + =+ =
=
The measure of the angle at the tail end of the kite is 58 .°
b. length: 8 cm; width: 5 cm; The dimensions doubled.
3. a. length: 6 units; width: 6 units
b. length: 48 in.; width: 48 in.
Sample answer: Use a proportion or a ratio table.
6×
6×
c. sketch length 6 units 1 unit
actual length 48 in. 8 in.= =
sketch width 6 units 1 unit
actual width 48 in. 8 in.= =
They are the same. The measurements in the drawing are proportional to the measurements of the actual painting.
4.
a. The size of the drawing decreases.
b. length: 2 units; width: 2 units; The dimensions are reduced by one third.
5. Sample answer: Increase or decrease each dimension of the drawing by the same factor.
6. Food court:
Painting:
Sample answer: The ratio of the perimeters for the original drawings to the actual objects is equal to the ratios found in Activities 1(c) and 3(c). The ratio of the areas for the original drawings to the actual objects is equal to the square of those ratios.
7. Answer should include, but is not limited to: Students will look at maps in books and on the Internet and make a list of all the different scales used on the maps.
8. When you zoom out, the measured distance stays the same and the actual distance increases. So, the scale decreases. When you zoom in, the measured distance stays the same and the actual distance decreases. So, the scale increases.
7.5 On Your Own (pp. 300–302)
1. The map distance is about 3 centimeters.
1 cm 3 cm
50 mi mi50 3
150
dd
d
=
= •=
The distance between Traverse City and Marquette is about 150 miles.
4. a. Because the drawing does not change size, the perimeter and area do not change.
b. 1 cm 4 cm
3 mm mm3 4
12
ss
s
=
= •=
The side length of the actual computer chip is 12 millimeters. So, the actual perimeter of the computer
chip is ( )4 12 48= millimeters and the actual area is
212 144= square millimeters.
c. 1 cm 10 mm 10scale factor
3 mm 3 mm 3= = =
drawing perimeter 16 cm 160 mm 10
actual perimeter 48 mm 48 mm 3= = =
2
2
2
2
2
2
2
drawing area 16 cm
actual area 144 mm
1 cm
9 mm
1 cm
3 mm
10 mm
3 mm
10
3
=
=
=
=
=
The ratios change but the overall relationship with the scale factor does not. The ratio of the perimeters is still the same as the scale factor, and the ratio of the areas is still the same as the square of the scale factor.
7.5 Exercises (pp. 303–305)
Vocabulary and Concept Check
1. A scale is a ratio that compares the measurements of the drawing or model with the actual measurements. A scale factor is a scale without any units.
2. The scale drawing is larger than the actual object because 2 centimeters is greater than 1 millimeter.
3. Convert one of the lengths into the same units as the other length. Then, form the scale and simplify.
Practice and Problem Solving
4. The drawing length is 5 centimeters.
1 cm 5 cm
5 ft ft5 5
25
=
= •=
xx
x
The actual length of the flower garden is 25 feet.
5. The rose bed is a square and its drawing has a side length of 2 centimeters.
1 cm 2 cm
5 ft ft5 2
10
=
= •=
xx
x
The actual dimensions of the rose bed are 10 feet by 10 feet.
6. The top perennial bed has a drawing length of 3 centimeters and width of 2 centimeters.
1 cm 3 cm
5 ft ft5 3
15
=
= •=
1 cm 2 cm
5 ft ft5 2
10
=
= •=
ww
w
( ) ( )2 2 2 15 2 10 30 20 50P w= + = + = + =
The actual perimeter of the top perennial bed is 50 feet.
The bottom perennial bed has a drawing length of 2 centimeters and width of 1.5 centimeters. From the top perennial bed, you know that 2 centimeters corresponds to 10 feet.
1 cm 1.5 cm
5 ft ft5 1.5
7.5
=
= •=
ww
w
( ) ( )2 2 2 10 2 7.5 20 15 35P w= + = + = + =
The actual perimeter of the bottom perennial bed is 35 feet.
7. The length of the tulip bed on the drawing is 3 centimeters and the width is 1.5 centimeters.
1 cm 3 cm
5 ft ft5 3
15
=
= •=
1 cm 1.5 cm
5 ft ft5 1.5
7.5
=
= •=
ww
w
( )15 7.5 112.5A w= = =
The area of the actual tulip bed is 112.5 square feet. From Exercise 5, the side length of the actual rose bed is
10 feet. So, the area of the actual rose bed is 210 100= square feet.
Area of tulip bed percent of area of rosebed
112.5 100
1.125
p
p
== •=
The area of the tulip bed is 112.5% of the area of the rose bed.
21. Answer should include, but is not limited to: a. Students will choose a product they want to advertise.
Students will design a billboard for the product. The billboard should contain words and a picture. The drawing of the billboard will be neat and labeled clearly.
b. Students will use the dimensions of their drawing of the billboard and the dimensions of the actual billboard to determine a scale factor for their picture.
22. a. The park has a drawing length of 12.5 centimeters and width of 2.5 centimeters.
( ) ( )2 2 2 12.5 2 2.5 25 5 30P w= + = + = + =
The perimeter of the park in the scale drawing is 30 centimeters.
( )( )12.5 2.5 31.25A w= = =
The area of the park in the scale drawing is 31.25 square centimeters.
b. 1 cm 12.5 cm
320 m m320 12.5
4000
=
= •=
1 cm 2.5 cm
320 m m320 2.5
800
www
=
= •=
( ) ( )2 2
2 4000 2 800
8000 1600
9600
P l w= +
= +
= +=
The actual perimeter of the park is 9600 meters.
( )( )4000 800 3,200,000A w= = =
The actual area of the park is 3,200,000 square meters.
23. a. The icon has the shape of a square and has a drawing side length of 4 centimeters.
( )4 4 4 16P s= = =
The perimeter of the icon in the scale drawing is 16 centimeters.
2 24 16A s= = =
The area of the icon in the scale drawing is 16 square centimeters.
b. 1 cm 4 cm
2.5 mm mm2.5 4
10
sss
=
= •=
( )4 4 10 40P s= = =
The actual perimeter of the icon is 40 millimeters.
2 210 100A s= = = The actual area of the icon is 100 square millimeters.
24. The ratio of the perimeters is the scale factor and the ratio of the areas is the square of the scale factor.
25. Original drawing
New drawing
Measurements in the new scale drawing will be 2 times the measurements in the original scale drawing.
27. The red region is in the shape of a trapezoid. The red region of the scale drawing has bases of 4 centimeters and 6 centimeters, and a height of 3 centimeters.
Let b and B be the actual bases and let h be the actual height.
1 cm 4 cm
1 ft ft1 4
4
bb
b
=
= •=
1 cm 6 cm
1 ft ft1 6
6
BB
B
=
= •=
1 cm 3 cm
1 ft ft1 3
3
hh
h
=
= •=
Use the formula for the area of a trapezoid to find the actual area.
( )( )( )
2
3 4 6 2
3 10 2
30 2
15
A h b B= + ÷
= + ÷
= ÷
= ÷=
The actual area of the red region is 15 square feet.
28. The blue region is in the shape of a trapezoid. The blue region of the scale drawing has bases of 1 centimeter and 2 centimeters, and a height of 3 centimeters.
Let b and B be the actual bases and let h be the actual height.
1 cm 1 cm
1 ft ft1b
b
=
=
1 cm 2 cm
1 ft ft1 2
2
BB
B
=
= •=
1 cm 3 cm
1 ft ft1 3
3
hh
h
=
= •=
Use the formula for the area of a trapezoid to find the actual area.
( )( )( )
2
3 1 2 2
3 3 2
9 2
4.5
A h b B= + ÷
= + ÷
= ÷
= ÷=
The actual area of the blue region is 4.5 square feet.
29. The green region is in the shape of a triangle. The green region of the scale drawing has a base of 2 centimeters and a height of 3 centimeters.
Let b be the actual bases and let h be the actual height.
1 cm 2 cm
1 ft ft1 2
2
bb
b
=
= •=
1 cm 3 cm
1 ft ft1 3
3
hh
h
=
= •=
Use the formula for the area of a triangle to find the actual area.
( )( )
( )( )
1
21
2 32
1 3
3
A bh=
=
=
=
The actual area of the green region is 3 square feet.
30. a. The length of the blueprint of the bathroom is
1 3
34 4 =
inch and the width is 1 1
2 inch.4 2 =
3in.1 in. 4
16 ft ft3
164
12
=
= •
=
1in.1 in. 2
16 ft ft1
162
8
=
= •
=
w
w
w
( )12 8 96A w= = =
The actual area of the bathroom floor is 96 square feet. So, it will cost 96 5 $480• = to tile the bathroom.
Because 1 inch corresponds to 16 feet, the actual length of the bedroom is 16 feet.
5 in.1 in. 4
16 ft ft5
164
20 ft
=
= •
=
w
w
w
Convert the dimensions to yards.
Length: 16 ft1 yd
3 ft× 1
5 yd3
=
Width: 20 ft1 yd
3 ft× 2
6 yd3
=
21 2 16 20 55 6 35 yd
3 3 3 3 9A w= = • = • =
The cost to carpet the bedroom is 5
18 35 $640.9
=
The length of the blueprint of the living room is
14 1 inch
4 =
and the width is 1 7
74 4 =
inches.
Because 1 inch corresponds to 16 feet, the actual length of the living room is 16 feet.
7 in.1 in. 4
16 ft ft7
164
28 ft
=
= •
=
w
w
w
Convert the dimensions to yards. You already know 1
16 ft 5 yards.3
= So, the length is 1
53
yards.
Width: 28 ft1 yd
3 ft× 1
9 yd3
=
21 1 16 28 75 9 49 yd
3 3 3 3 9A w= = • = • =
The cost to carpet the living room is
718 49 $896.
9 =
So, the total cost to carpet the
bedroom and the living room is $640 $896 $1536.+ =
c. Convert square yards to square feet.
2
2 23 ft1 yd 1 yd
1 yd
× =
2
2
9 ft
1 yd× 29 ft=
Carpet unit cost: 2 2 2
$18 $18 $2
1 yd 9 ft 1 ft= =
Tile unit cost: 2
$5
1 ft
Because $5 per square foot is greater than $2 per square foot, the tile has a higher unit cost.
31. Sample answer: The radius of a baseball is about 3 inches. So, if you use a baseball as a scale model of Earth, the scale is:
3 in. 1 in.
.6378 km 2126 km
=
Then the radius of the model for the Sun would be:
1 in. in.
2126 km 695,500 km
695,500 2126
327
=
=≈
x
x
x
Because 327 inches is about 27 feet long, your model for the Sun would be quite large. So, it is not reasonable to choose a baseball as a model of Earth.