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Two tangents AT and BT touch a circle at A and B

Source: Canadian RepĂȘchage 2010: Problem 2

May 6, 2014
geometryrectanglegeometry proposed

Problem Statement

Two tangents ATAT and BTBT touch a circle at AA and BB, respectively, and meet perpendicularly at TT. QQ is on ATAT, SS is on BTBT, and RR is on the circle, so that QRSTQRST is a rectangle with QT=8QT = 8 and ST=9ST = 9. Determine the radius of the circle.