Exercise 42 Page 557

Let's recall the definition of similar polygons. Two polygons are similar if and only if their corresponding angles are congruent and corresponding side lengths are proportional. Notice that not all of the pairs of right triangles satisfy the above conditions, as we only know that all of them have one right angle. However, we can find pairs of right triangles where the rest of the corresponding angles are congruent and where corresponding side lengths are proportional. Therefore, two right triangles are sometimes similar polygons.