MathDB
Maximum area

Source: 2009 AIME I #15

March 18, 2009
geometryincentercircumcircletrigonometryAMCAIMEperpendicular bisector

Problem Statement

In triangle ABC ABC, AB \equal{} 10, BC \equal{} 14, and CA \equal{} 16. Let D D be a point in the interior of BC \overline{BC}. Let IB I_B and IC I_C denote the incenters of triangles ABD ABD and ACD ACD, respectively. The circumcircles of triangles BIBD BI_BD and CICD CI_CD meet at distinct points P P and D D. The maximum possible area of BPC \triangle BPC can be expressed in the form a\minus{}b\sqrt{c}, where a a, b b, and c c are positive integers and c c is not divisible by the square of any prime. Find a\plus{}b\plus{}c.