A problem based on the Finsler-Hadwiger theorem

The Problem

If you build squares off 2 sides of any triangle, you’re guaranteed a hidden 45-45-90 triangle.

Exploring the solution involving successive tranformations of a point.

M' is the rotation of the point M around D by 90°(CCW). M'' is the rotation of the point M' around the point E by 90°(CCW). Rotation of this point M'' around the point F by 180° brings it back to the point M. You can see this for yourself by moving the point M in the applet. What if the point M coincides with the point A? What if the point M coincides with the point D? Use the given buttons to see. To change the sizes of the two squares move the blue coloured points.