1981 AHSME Problems/Problem 27

Problem

In the adjoining figure triangle $ABC$ is inscribed in a circle. Point $D$ lies on $\stackrel{\frown}{AC}$ with $\stackrel{\frown}{DC} = 30^\circ$ , and point $G$ lies on $\stackrel{\frown}{BA}$ with $\stackrel{\frown}{BG}\, > \, \stackrel{\frown}{GA}$ . Side $AB$ and side $AC$ each have length equal to the length of chord $DG$ , and $\angle CAB = 30^\circ$ . Chord $DG$ intersects sides $AC$ and $AB$ at $E$ and $F$ , respectively. The ratio of the area of $\triangle AFE$ to the area of $\triangle ABC$ is

[asy] defaultpen(linewidth(.8pt)); pair C = origin; pair A = 2.5*dir(75); pair B = A + 2.5*dir(-75); path circ =circumcircle(A,B,C); pair D = waypoint(circ,(7/12)); pair G = waypoint(circ,(1/6)); pair E = intersectionpoint(D--G,A--C); pair F = intersectionpoint(A--B,D--G); label(" $A$ ",A,N); label(" $B$ ",B,SE); label(" $C$ ",C,SW); label(" $D$ ",D,SW); label(" $G$ ",G,NE); label(" $E$ ",E,NW); label(" $F$ ",F,W); label(" $30^\circ$ ",A,12S+E,fontsize(6pt)); draw(A--B--C--cycle); draw(circ); draw(Arc(A,0.25,-75,-105)); draw(D--G); [/asy] $\textbf{(A)}\ \dfrac {2 - \sqrt {3}}{3}\qquad \textbf{(B)}\ \dfrac {2\sqrt {3} - 3}{3}\qquad \textbf{(C)}\ 7\sqrt {3}-12\qquad \textbf{(D)}\ 3\sqrt {3}-5\qquad\\ \textbf{(E)}\ \dfrac {9-5\sqrt {3}}{3}$

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1981 AHSME Problems/Problem 27

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