TRIANGLES
Triangles in General
The three interior angles of any triangle add up to 180°. In this figure, x + 50 + 100 = 180, so x = 30.
An exterior angle of a triangle is equal to the sum of the remote interior angles. In this figure, the exterior angle labeled y° is equal
to the sum of the remote angles: y = 40 + 95 = 135.