Shape and Space DEGREE
Dec 31, 2015
Shape and Space
DEGREE
DEGREE
We use degrees (e.g. 90°) to measure angles
Right Angle(90°)
Straight Line(180°)
Full Turn(360 °)
Acute Angle(less than 90°)
Obtuse Angle(less than 180°, more than 90°)
Reflex Angle(less than 360°, more than 180°)
EXERCISES
Describe the following as:
a) Right Angle b) Straight Line c) Acute Angle d) Obtuse Angle e) Reflex Angle
3) 4)
5)6)
7) 8)
9)
10)11)
1) 2)
MEASURING ANGLES
We use a PROTRACTOR to measure angles.
A protractor has a clockwise and anticlockwise scale
If an angle turns (opens) clockwise
you must use the external scale
If an angle turns (opens) anticlockwise
you must use the internal scale
MEASURING ANGLES
Step 1: Put the centre of the
protractor on the corner of the angle
Step 2: Turn the protractor so that
0° is on one of the lines
Step 3: Start to count in the direction
of the angle 10°, 20°, 30° etc 10°
20°
30°
50°
40°
70°60°
0°
Cwblhewch y taflenni gwaithComplete the worksheets
CREATING A 70° ANGLE
Step 1: Put the centre of the
protractor on the end of a straight line
Step 2: Turn the protractor so that
0° is on the line
Step 3: Start to count in the direction
of the angle 10°, 20°, 30° etc
Step 4: Put a dot on 70°
Step 5: Connect the dot with the end
of the straight line
10°
20°
30°
50°
40°
70°60°
0°
70°70°
EXERCISES
Using a Protractor and Ruler,
create these angles in your books.
Label each angle like this :-
a) 60°b) 45°c) 130°d) 145°e) 75°
f) 105°g) 57°h) 168°i) 23°
35°
STRAIGHT LINE (180°)
We don’t always find angles by measuring. We can calculate angles.
Angles on a straight line add to 180°
80°a
a = 180° – 80°a = 100°
162°b
b = 180° – 162°b = 18°
EXERCISES
Calculate the angles labelled with letters
50°a
138°
cb65°
d
117°
72°e
103°f
30°g
20°
50°
h100°
i
64°
FULL TURN (360°)
We don’t always find angles by measuring. We can calculate angles.
Angles around a point make a full turn.
They add to make a total of 360°
290°
a
235°b
a = 360° – 290°a = 70°
b = 360° – 235°b = 125°
EXERCISES
Calculate the angles labelled with letters
285°
a82°
b
c
32°
d24°
130°
e
170°
147°
f
g
156°44°
h
88°134°
OPPOSITE
We don’t always find angles by measuring. We can calculate angles
The OPPOSITE angles are equal. This happens when two lines cross each other.One RED ANGLE and one BLUE ANGLE add to 180°
120°
60° q
p
150°x
zy
q = 60°p = 120°
y = 150°x = 30°z = 30°
EXERCISES
Calculate the angles labelled with letters
a 40°135°
b
cd
145°35°
29°151°
fe40°
i
g
h
150°
kL j
35°
m
n o 77°pq
r
tu
s