Find the measure of each exterior angle of an equilateral triangle.

Question

Philoid · Accepted Answer

From the figure, we have

∠AOD is the exterior angle

∴ ∠AOD + ∠AOB = 180^o

60^o + ∠AOB = 180^o

∠AOB = 180^o – 60^o

∠AOB = 120^o

Hence, the measure of each of the exterior angle of an equilateral triangle is 120^o