Page 3 - ANS SUB

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of their measures is 180 .
7. In the adjoining figure, AOB is a straight line. Find the value of ‘x’.

Solution:
∠AOC and ∠BOC are a linear pair of angles.
∠AOC + ∠BOC = 180 0
0
0
62 + x = 180 0
0
0
x = 180 – 62
0
x= 118
0
Therefore, the value of x is 118 .

8. In the adjoining figure, AOB is a straight line. Find the value of x.

Hence, find ∠AOC and ∠BOD.

Solution:
AOB is a straight line.
0
∠AOB = 180
0
∠AOC + ∠COD + ∠BOD = 180
0
0
0
0
(3x – 7) + 55 + (x + 20) = 180
0
0
0
0
3x – 7 + 55 + x + 20 = 180
0
0
4x + 68 = 180
0
4x = 112
0
x = 28
0
∠AOC = (3x – 7)
0
0
= 3(28 ) – 7
0
0
= 84 – 7
0
= 77
0
∠BOD = (x + 20)
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