MathDB
AX x BY = AI x BI, circle with center a midpoint, triangle with that incircle

Source: 2014 NZOMC Camp Selections p9

January 10, 2021
geometryincircle

Problem Statement

Let ABAB be a line segment with midpoint II. A circle, centred at II has diameter less than the length of the segment. A triangle ABCABC is tangent to the circle on sides ACAC and BCBC. On ACAC a point XX is given, and on BCBC a point YY is given such that XYXY is also tangent to the circle (in particular XX lies between the point of tangency of the circle with ACAC and CC, and similarly YY lies between the point of tangency of the circle with BCBC and CC. Prove that AXBY=AIBIAX \cdot BY = AI \cdot BI.