MathDB
Circle, chords, and area of the circle

Source: AHSME 1995 #26

November 21, 2005
geometryPythagorean Theorempower of a pointAMC

Problem Statement

In the figure, AB\overline{AB} and CD\overline{CD} are diameters of the circle with center OO, ABCD\overline{AB} \perp \overline{CD}, and chord DF\overline{DF} intersects AB\overline{AB} at EE. If DE=6DE = 6 and EF=2EF = 2, then the area of the circle is [asy] size(120); defaultpen(linewidth(0.7)); pair O=origin, A=(-5,0), B=(5,0), C=(0,5), D=(0,-5), F=5*dir(40), E=intersectionpoint(A--B, F--D); draw(Circle(O, 5)); draw(A--B^^C--D--F); dot(O^^A^^B^^C^^D^^E^^F); markscalefactor=0.05; draw(rightanglemark(B, O, D)); 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("FF", F, dir(O--F)); label("OO", O, NW); label("EE", E, SE);[/asy] <spanclass=latexbold>(A)</span> 23π<spanclass=latexbold>(B)</span> 472π<spanclass=latexbold>(C)</span> 24π<spanclass=latexbold>(D)</span> 492π<spanclass=latexbold>(E)</span> 25π<span class='latex-bold'>(A)</span>\ 23\pi \qquad <span class='latex-bold'>(B)</span>\ \dfrac{47}{2}\pi \qquad <span class='latex-bold'>(C)</span>\ 24\pi \qquad <span class='latex-bold'>(D)</span>\ \dfrac{49}{2}\pi \qquad <span class='latex-bold'>(E)</span>\ 25\pi