Understand and use the sum of angles on
a straight line
1
Two angles,
a and b, are adjacent on a straight line.
a) Measure angles a and b.
a = b =
b) What is the total of the two angles?
c) Complete the sentence.
Adjacent angles on a straight line
2
Tick the diagram that shows adjacent angles on a straight line.
3
Work out the unknown angles.
a)
d)
e = a =
b) e)
g = y =
c) f)
x = z =
4
Do you agree with Tommy?
Explain your answer.
© White Rose Maths 2020
a
b
e
g
y
a
x
z
58°
141°
62°
132°
49°
43°
37°
Angle b is 116°
because angles on a straight
line add up to 180°.
b
64°
5
Use the information to work out the unknown angles.
a) Angle
a is half the size of angle b.
a =
b =
b) Angle a is four times the size of angle b.
a =
b =
6
a) Write the size of the given angles.
ABD
EBC
DBE
b) Is ABC a straight line?
How do you know?
© White Rose Maths 2020
7
Work out the value of
x.
a) b)
x = x =
Compare methods with a partner.
8
AB and CD are straight lines.
Write expressions for the sizes of any missing angles and label
them on the diagram.
a
b
38°
97°
45°
A
B
C
D
E
a
b
x
2x
x
2x
A
B
C
D
E
y
x
