MathDB
Two Circumcircles

Source: AIME II 2010 Problem #15

April 1, 2010
geometrycircumcircleratiogeometric transformationSpiral Similarityangle bisectorAIME

Problem Statement

In triangle ABC ABC, AC \equal{} 13, BC \equal{} 14, and AB\equal{}15. Points M M and D D lie on AC AC with AM\equal{}MC and \angle ABD \equal{} \angle DBC. Points N N and E E lie on AB AB with AN\equal{}NB and \angle ACE \equal{} \angle ECB. Let P P be the point, other than A A, of intersection of the circumcircles of AMN \triangle AMN and ADE \triangle ADE. Ray AP AP meets BC BC at Q Q. The ratio BQCQ \frac{BQ}{CQ} can be written in the form mn \frac{m}{n}, where m m and n n are relatively prime positive integers. Find m\minus{}n.