Question:
In the below fig. rays AB and CD intersect at O.
(I) Determine y when x = 60
(ii) Determine x when y = 40
Solution:
(i) Given x = 60
AOC, BOC are linear pair of angles
∠AOC + ∠BOC = 180°
⟹ 2x + y = 180
⟹ 2(60) + y = 180 [since x = 60]
⟹ y = 60
(ii) Given y = 40
AOC and BOC are linear pair of angles
∠AOC + ∠BOC = 180°
⟹ 2x + y = 180
⟹ 2x + 40 = 180
⟹ 2x =180 - 140
⟹ 2x = 140
⟹ x = 70