Let ABC be a triangle. Let M and N be the points in which the median and the angle bisector, respectively, at A meet the side BC. Let Q and P be the points in which the perpendicular at N to NA meets MA and BA, respectively. And O the point in which the perpendicular at P to BA meets AN produced.
Prove that QO is perpendicular to BC. ratiogeometrycircumcircletrigonometryangle bisectorperpendicular bisector