83-Six points lie on a circle associated Botema configuration

Let $ABC$ be a triangle $M_a$ is midpoint of $BC$, $H$ is the orthocenter of the triangle $ABC$. Let $V_A$, $V_B$, $V'_A$, $V'_B$ are center of four squares. Show that six points $V_A,$ $V'_a,$ $M_a,$ $H_a,$ $V_B,$ $V'_B$  lie on a circle.

82-A generalization Pythagoras' Theorem

81-Two conic problem

 Let two conics through four common points $A,B,C,D$. Tangent line of the first conic  at $B,D$ meets the second conic at $G,H$ respectively. Show that $AC,BD,GH$ are concurrent