Difference between revisions of "2006 AMC 12B Problems/Problem 15"

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(Problem)
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== Problem ==
 
== Problem ==
{{problem}}
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Circles with centers <math> O</math> and <math> P</math> have radii 2 and 4, respectively, and are externally tangent.  Points <math> A</math> and <math> B</math> are on the circle centered at <math> O</math>, and points <math> C</math> and <math> D</math> are on the circle centered at <math> P</math>, such that <math> \overline{AD}</math> and <math> \overline{BC}</math> are common external tangents to the circles.  What is the area of hexagon <math> AOBCPD</math>?
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<asy>
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// from amc10 problem series
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unitsize(0.4 cm); defaultpen(linewidth(0.7) + fontsize(11));
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pair A, B, C, D;
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pair[] O;
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O[1] = (6,0);
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O[2] = (12,0);
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A = (32/6,8*sqrt(2)/6);
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B = (32/6,-8*sqrt(2)/6);
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C = 2*B;
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D = 2*A;
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draw(Circle(O[1],2));
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draw(Circle(O[2],4));
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draw((0.7*A)--(1.2*D));
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draw((0.7*B)--(1.2*C));
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draw(O[1]--O[2]);
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draw(A--O[1]);
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draw(B--O[1]);
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draw(C--O[2]);
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draw(D--O[2]);
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label("$A$", A, NW);
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label("$B$", B, SW);
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label("$C$", C, SW);
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label("$D$", D, NW);
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dot("$O$", O[1], SE);
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dot("$P$", O[2], SE);
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label("$2$", (A + O[1])/2, E);
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label("$4$", (D + O[2])/2, E);</asy>
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<math> \textbf{(A) } 18\sqrt {3} \qquad \textbf{(B) } 24\sqrt {2} \qquad \textbf{(C) } 36 \qquad \textbf{(D) } 24\sqrt {3} \qquad \textbf{(E) } 32\sqrt {2}</math>
  
 
== Solution ==
 
== Solution ==

Revision as of 22:14, 28 October 2011

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Problem

Circles with centers $O$ and $P$ have radii 2 and 4, respectively, and are externally tangent. Points $A$ and $B$ are on the circle centered at $O$, and points $C$ and $D$ are on the circle centered at $P$, such that $\overline{AD}$ and $\overline{BC}$ are common external tangents to the circles. What is the area of hexagon $AOBCPD$?

[asy] // from amc10 problem series unitsize(0.4 cm); defaultpen(linewidth(0.7) + fontsize(11)); pair A, B, C, D; pair[] O; O[1] = (6,0); O[2] = (12,0); A = (32/6,8*sqrt(2)/6); B = (32/6,-8*sqrt(2)/6); C = 2*B; D = 2*A; draw(Circle(O[1],2)); draw(Circle(O[2],4)); draw((0.7*A)--(1.2*D)); draw((0.7*B)--(1.2*C)); draw(O[1]--O[2]); draw(A--O[1]); draw(B--O[1]); draw(C--O[2]); draw(D--O[2]); label("$A$", A, NW); label("$B$", B, SW); label("$C$", C, SW); label("$D$", D, NW); dot("$O$", O[1], SE); dot("$P$", O[2], SE); label("$2$", (A + O[1])/2, E); label("$4$", (D + O[2])/2, E);[/asy]

$\textbf{(A) } 18\sqrt {3} \qquad \textbf{(B) } 24\sqrt {2} \qquad \textbf{(C) } 36 \qquad \textbf{(D) } 24\sqrt {3} \qquad \textbf{(E) } 32\sqrt {2}$

Solution

See also

2006 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 14
Followed by
Problem 16
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All AMC 12 Problems and Solutions