Vietnam TST 2017 problem 4
Source: Vietnam TST 2017
March 26, 2017
geometryVietnamTST
Problem Statement
Triangle is inscribed in circle . varies on such that . is the midpoint of . The circle with diameter intersects at . intersects at and intersects at . The circle with diameter intersects at in this order.
a. Prove that passes through the midpoint of .
b. Let be the midpoint of . The radical axis of circles with diameters intersects at . Prove that always passes through a fixed point.