Diameter Section Maximization
Source: AIME 2009II Problem 15
April 2, 2009
trigonometryratioAMCAIME
Problem Statement
Let be a diameter of a circle with diameter . Let and be points on one of the semicircular arcs determined by such that is the midpoint of the semicircle and MB\equal{}\frac35. Point lies on the other semicircular arc. Let be the length of the line segment whose endpoints are the intersections of diameter with the chords and . The largest possible value of can be written in the form r\minus{}s\sqrt{t}, where , , and are positive integers and is not divisible by the square of any prime. Find r\plus{}s\plus{}t.