Let AD is centroid of ABC triangle. Let (d) is the perpendicular line with AD. Let M is a point on (d). Let E,F are midpoints of MB,MC respectively. The line through point E and perpendicular with (d) meet AB at P. The line through point F and perpendicular with (d) meet AC at Q. Let (d′) is a line through point M and perpendicular with PQ. Prove (d′) always pass a fixed point. geometrycircumcircleanalytic geometrygraphing linesslopeparallelogramgeometric transformation