WATCH: What are congruent and similar shapes ... add up to 180 degrees A simple guide on how to show the angles in triangle add up to 180 degrees, aimed at students aged 11 to 14.

CD and FG are the same length. AD and EF are the same length. Image caption, Angles in congruent shapes are equal. Angle A and angle E are equal. They correspond to each other. Angle B and angle H ...