# Similar Triangles?

You can move points A, B, and C.
Point D slides along the edge AB.
Line DF is parallel to AC
Line DE is parallel to BC

Are the blue and yellow triangles similar? How could you convince someone?
Are the blue and yellow triangles ever congruent? When?
When is the white area the same as the sum of the blue and yellow areas? Why?

Download our apps here: