In the figure above, x + 50 + 100 = 180, so x = 30.
Measure of an exterior angle: The measure of an exterior angle of a triangle
is equal to the sum of the measures of the remote interior angles.
In the figure above, the measure of the exterior angle labeled y° is equal to the
sum of the measures of the remote interior angles: y = 50 + 100 = 150.
Sum of the exterior angles: The measures of the three exterior angles of any
triangle add up to 360°.
In the figure above, a + b + c = 360. (Note: In fact, the measures of the exterior
angles of any polygon add up to 360°.) Area formula: The general formula for