MathDB
Find CD

Source: 1971 AHSME Problem 31

April 24, 2014
AwesomeMathsummer programLaTeXAMC

Problem Statement

[asy] size(2.5inch); pair A = (-2,0), B = 2dir(150), D = (2,0), C; draw(A..(0,2)..D--cycle); C = intersectionpoint(A..(0,2)..D,Circle(B,arclength(A--B))); draw(A--B--C--D--cycle); label("AA",A,W); label("BB",B,NW); label("CC",C,N); label("DD",D,E); label("44",A--D,S); label("11",A--B,E); label("11",B--C,SE); //Credit to chezbgone2 for the diagram[/asy]
Quadrilateral ABCDABCD is inscribed in a circle with side ADAD, a diameter of length 44. If sides ABAB and BCBC each have length 11, then side CDCD has length
<spanclass=latexbold>(A)</span>72<spanclass=latexbold>(B)</span>522<spanclass=latexbold>(C)</span>11<spanclass=latexbold>(D)</span>13<spanclass=latexbold>(E)</span>23<span class='latex-bold'>(A) </span>\frac{7}{2}\qquad<span class='latex-bold'>(B) </span>\frac{5\sqrt{2}}{2}\qquad<span class='latex-bold'>(C) </span>\sqrt{11}\qquad<span class='latex-bold'>(D) </span>\sqrt{13}\qquad <span class='latex-bold'>(E) </span>2\sqrt{3}