MathDB
Diameter Section Maximization

Source: AIME 2009II Problem 15

April 2, 2009
trigonometryratioAMCAIME

Problem Statement

Let MN \overline{MN} be a diameter of a circle with diameter 1 1. Let A A and B B be points on one of the semicircular arcs determined by MN \overline{MN} such that A A is the midpoint of the semicircle and MB\equal{}\frac35. Point C C lies on the other semicircular arc. Let d d be the length of the line segment whose endpoints are the intersections of diameter MN \overline{MN} with the chords AC \overline{AC} and BC \overline{BC}. The largest possible value of d d can be written in the form r\minus{}s\sqrt{t}, where r r, s s, and t t are positive integers and t t is not divisible by the square of any prime. Find r\plus{}s\plus{}t.