MathDB
Right triangle with vertices as centers of circles

Source: AMC 12 2006A, Problem 13

February 5, 2006
geometryalgebrasystem of equationsAMC

Problem Statement

The vertices of a 3 \minus{} 4 \minus{} 5 right triangle are the centers of three mutually externally tangent circles, as shown. What is the sum of the areas of the three circles? [asy]unitsize(5mm); defaultpen(fontsize(10pt)+linewidth(.8pt));
pair B=(0,0), C=(5,0); pair A=intersectionpoints(Circle(B,3),Circle(C,4))[0];
draw(A--B--C--cycle); draw(Circle(C,3)); draw(Circle(A,1)); draw(Circle(B,2));
label("AA",A,N); label("BB",B,W); label("CC",C,E); label("3",midpoint(B--A),NW); label("4",midpoint(A--C),NE); label("5",midpoint(B--C),S);[/asy]<spanclass=latexbold>(A)</span>12π<spanclass=latexbold>(B)</span>25π2<spanclass=latexbold>(C)</span>13π<spanclass=latexbold>(D)</span>27π2<spanclass=latexbold>(E)</span>14π <span class='latex-bold'>(A) </span> 12\pi\qquad <span class='latex-bold'>(B) </span> \frac {25\pi}{2}\qquad <span class='latex-bold'>(C) </span> 13\pi\qquad <span class='latex-bold'>(D) </span> \frac {27\pi}{2}\qquad <span class='latex-bold'>(E) </span> 14\pi