TWO SQUARES HANGING from a CORNER // DOS CUADRADOS COLGAN DE UNA ESQUINA

                     Let $ABCD$ and $AEFG$ be two squares. Then $BE \underset{=}{\perp}DG$.

     Attention, the notation order of the tops of the two squares is counter-clockwise.

              This property, which we will demonstrate as a Lemma, was used to solve a problem from a Facebook group.