Question

In the given figure, the directed lines are parallel to each other. Find the unknown angles.

Answer 1

∵ Lines are parallel

∠a = ∠1 and ∠c = ∠2 .........(alternate angles)

But ∠1 + 115° = 180° .........(linear pair)

∴ ∠1 = 180°− 115° = 65°

Similarly ∠2 + 120° = 180°

∴ ∠2 = 180°− 120° = 60°

∴ ∠a = ∠1 = 65°, ∠c = ∠2 = 60°

But a + c + c = 180° ............(angles on a line)

⇒ 65° + b + 60° = 180°

⇒ b + 125° = 180°

⇒ b = 180°− 125° = 55°

Hence a = 65°, b = 55°, c =60°