Thread: Triangle

Problem:

H is the orthocenter of acute triangle ABC, from A, draw the two tangent lines AP and AQ of the circle whose diameter is BC, the points of tangency are P, Q respectively. Prove: P, H, Q are collinear.

• Let be the circle with diameter
• Let & be the projections of & to & respectively.
• In the cyclic quadrilateral with & yields that is on the polar line of