# Problem #2186

 2186 Circles with centers $O$ and $P$ have radii $2$ and $4$, respectively, and are externally tangent. Points $A$ and $B$ on the circle with center $O$ and points $C$ and $D$ on the circle with center $P$ are such that $AD$ and $BC$ are common external tangents to the circles. What is the area of the concave hexagon $AOBCPD$? $[asy] unitsize(.7cm); defaultpen(.8); pair O = (0,0), P = (6,0), Q = (-6,0); pair A = intersectionpoint( arc( (-3,0), (0,0), (-6,0) ), circle( O, 2 ) ); pair B = (A.x, -A.y ); pair D = Q + 2*(A-Q); pair C = Q + 2*(B-Q); draw( circle(O,2) ); draw( circle(P,4) ); draw( (Q + 0.8*(A-Q)) -- ( Q + 2.3*(A-Q) ) ); draw( (Q + 0.8*(B-Q)) -- ( Q + 2.3*(B-Q) ) ); draw( A -- O -- B ); draw( C -- P -- D ); draw( O -- P ); label("O",O,W); label("P",P,E); label("A",A,NNW); label("B",B,SSW); label("D",D,NNW); label("C",C,SSW); [/asy]$ $\mathrm{(A) \ } 18\sqrt{3}\qquad \mathrm{(B) \ } 24\sqrt{2}\qquad \mathrm{(C) \ } 36\qquad \mathrm{(D) \ } 24\sqrt{3}\qquad \mathrm{(E) \ } 32\sqrt{2}$ This problem is copyrighted by the American Mathematics Competitions.
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• Reduce fractions to lowest terms and enter in the form 7/9.
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