Question

Apply what you know about triangles to find the missing angle measures in the figure.

Answer 1

Since, by the definition of exterior angle of an triangle,

b + 60° = 125°

⇒ b = 65°

By the angle sum property of triangle,

a + b + 60° = 180°

⇒ a + 65° + 60° = 180°

⇒ a + 125° = 180°

⇒ a = 55°

By the linear angle postulate,

60° + d + 90° = 180°

d + 150° = 180°

d = 30°

Again, by the angle sum property of triangle,

c + d + 90° = 180°

c + 30° + 90° = 180°

c + 120° = 180°

c = 60°