Phil. 4 

Answer to the triangle problem 





Perhaps you falsely assumed that these were really triangles. To the naked eye, the "apparent hypotenuses" of the big triangles look like straight lines, but each consists of two straight line segments with slightly different slopes. So, the two red triangles are not congruent; nor are the two dark green triangles. Sleazy. Euclid can rest in peace. Thanks to Andre Routh for this explanation. 