My older son is reviewing Art of Problem Solving’s Introduction to Geometry book this summer. Today he was working on problem relating to similar triangles, and the problem he picked for our movie was a fairly plain vanilla similar triangles problem:

The first part of the problem when smoothly, but the second part gave him some trouble. It was interesting to see his struggle to find the correct set of triangles to compare in the second part. Once you find them the problem is a snap – but finding them isn’t necessarily so easy when you are learning geometry. Staying with the problem might be the biggest lesson here.