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SAUDI ARABIAN MATHEMATICAL COMPETITIONS

Saudi Arabia geometry

Problem

Let be an acute, non-isosceles triangle which is inscribed in a circle . A point belongs to the segment . Denote by and the projections of on and , respectively. Suppose that the line intersects at ( is between and is between ). Prove the following assertions:

1. If is the center of the circle , then is tangent to . 2. If is the midpoint of , then is equal to 4 times the distance between the centers of two circles and .
Solution
See the solution to Problem 1 in the test of level 4+.

Techniques

TangentsRadical axis theoremAngle chasingCartesian coordinates