Area of a Trapezoid. Find the area of each figure. 1. 2. Find each missing measure. 3. Area = 100 in 2 4. Area = 25.2 cm 2 x 10.5 h 2.3 ft 2 10.

Area of a Trapezoid

Find the area of each figure.

1.

2.

Find each missing measure.

3. Area = 100 in2

4. Area = 25.2 cm2

x

10.5

h

2.3 ft

2

10

10

Quadrilateral:4 sides

Trapezoid:

Quadrilateral with only one pair of parallel sides.

b1

b2

)(2

1A 21 bbh

h is height

b1 is base #1

b2 is base #2

Show video http://www.youtube.com/watch?v=9jxMI4O4jb0&NR=1

http://www.mathplayground.com/howto_area_trapezoid.html

http://www.youtube.com/watch?v=-_HxRZ4keTU&feature=related

http://www.mathopenref.com/trapezoidarea.html

http://www.youtube.com/watch?v=2PhMRRBVvEg&NR=1

nerdy http://www.youtube.com/watch?v=W2Ghl33EdOs&NR=1

Find the area of the trapezoid.

Write the trapezoid area formula.

Substitute all known values.

Add numbers in parentheses.

Multiply.

The area of the trapezoid is 28 ft2.

)(2

1A 21 bbh

)95)(4(2

1A

)14)(4(2

1A

28A

Find the height of the trapezoid. The trapezoid’s area is 17.5 cm2.

Write the trapezoid area formula.

Substitute all known values.

Add numbers in parentheses.

Multiply on the right side.

Divide by 7

The height of the trapezoid is 2.5 cm.

)(2

1A 21 bbh

)86(2

15.17 h

)14(2

15.17 h

7

7

7

5.17 h

h5.2

h75.17

1. Find the area of the trapezoid.

2. The area of the trapezoid is 82 square inches. Find the height.

9 m

6.2 m

5 m

17 in

24 in

h

How can the area of a trapezoid be explained or broken down using other geometric shapes and area formulas?

Explain how the “average” is used in the formula for area of a trapezoid.

Target:Understand and use the trapezoid area formula

Nakisha painted a large trapezoid-shaped mural. The areaof the mural is 88 square feet. The longer base is 20 feet.The height is 6.4 feet. Find the length of the missing base.

Draw the figure.

Write the formula.

Substitute given information.

)(2

1A 21 bbh

)20)(4.6(2

188 1 b

Nakisha painted a large trapezoid-shaped mural. The area of the mural is 88 square feet. The longer base is 20 feet. The height is 6.4 feet. Find the length of the missing base.

Multiply and 6.4.

Distribute 3.2.

Subtract 64 from each side.

Divide by 3.2

The length of the missing base is 7.5 feet.

)20(2.388 1 b

642.388 1 b6464

12.324 b

2.3

2.3

2.3

24 1b

15.7 b

21