MathDB
Concentric Squares

Source:

January 5, 2007
geometryperimeterAMCAIMEnumber theoryrelatively primeAIME I

Problem Statement

The two squares shown share the same center OO and have sides of length 1. The length of AB\overline{AB} is 43/9943/99 and the area of octagon ABCDEFGHABCDEFGH is m/n,m/n, where mm and nn are relatively prime positive integers. Find m+n.m+n. [asy] real alpha = 25; pair W=dir(225), X=dir(315), Y=dir(45), Z=dir(135), O=origin; pair w=dir(alpha)*W, x=dir(alpha)*X, y=dir(alpha)*Y, z=dir(alpha)*Z; draw(W--X--Y--Z--cycle^^w--x--y--z--cycle); pair A=intersectionpoint(Y--Z, y--z), C=intersectionpoint(Y--X, y--x), E=intersectionpoint(W--X, w--x), G=intersectionpoint(W--Z, w--z), B=intersectionpoint(Y--Z, y--x), D=intersectionpoint(Y--X, w--x), F=intersectionpoint(W--X, w--z), H=intersectionpoint(W--Z, y--z); dot(O); label("OO", O, SE); label("AA", A, dir(O--A)); label("BB", B, dir(O--B)); label("CC", C, dir(O--C)); label("DD", D, dir(O--D)); label("EE", E, dir(O--E)); label("FF", F, dir(O--F)); label("GG", G, dir(O--G)); label("HH", H, dir(O--H));[/asy]