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Q In the diagram, AOD is a straight line. Calculate angle a.
B
C
a
Z0 + Zb = 90° A nX43° D
Two angles that add 0
up to 90° are called
complementary angles. 90° + o + 43° = 180° (zls on a str. line) Remember to state the reason
'Z.S on a str. line'.
0= 180°-43°-90°
= 47°
Q In the diagram, PR is a straight line. Calculate the value of b in the diagram.
00
^x+Z.y=180° 1|
Two angles that add
up to 180° are called '
supplementary angles. 2b° + 10°p>;? lb" + 10° + 3b° = 180° (^s on a str. line)
5b° = 180° -10°
= 170°
b =™
Check My 5
= 34
Understanding
O In each diagram, there is one straight line. Calculate the size of the unknown angle.
a) b) d) e)
^9^
Wd
124" \
90°l_ e
f) 9) h) i) j)
>
V
X51° N. 124° _ 78°AA70°
42V'V---/
k) 1) m) n) 0)
boy \34\n
k m jyy>^
r^Y30° "1
Conclusion The angles on a straight line add up to
UNIT 6 Angles and Their Properties
