Page 4 - ANS SUB

0
= (28 + 20)
0
= 48
0
9. Two lines AB and CD intersect at O. If ∠AOC = 50 , find ∠AOD, ∠BOD and
∠BOC.

Solution:
∠AOC and ∠AOD form a linear pair.
0
∠AOC + ∠AOD = 180
0
0
50 + ∠AOD = 180
0
0
∠AOD = 180 – 50
0
∠AOD = 130
∠AOD and ∠BOC are vertically opposite angles
So,
0
∠AOD = ∠BOC = 130
0
∠AOC = ∠BOD = 50
10. In the adjoining figure, three coplanar lines AB, CD and EF intersect at a
point O, forming Angles as shown. Find the values of x, y, z and t.

Solution:
From the figure we know that ∠COE and ∠DOF are vertically opposite angles.
0
∠COE = ∠DOF = ∠z = 50
∠BOD and ∠COA are vertically opposite angles
0
∠BOD = ∠COA = ∠t = 90
∠COA and ∠AOD form a linear pair
0
∠COA + ∠AOD = 180
0
∠COA + ∠AOF + ∠FOD = 180
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