Triangle Proportionality_GSEGeom

Points A, B, C, and D can be moved freely to create an infinite number of similar triangles. Segment DE is always parallel to side BC. How is the Triangle Proportionality Theorem demonstrated?

Answer the following questions

How can you prove that triangles ABC and ADE are similar?

How can you prove that the triangles ABC and ADE are similar?

What scale factor relates BC to DE?