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Source: — Problem Solving |

by 800GMAT » Mon Apr 02, 2007 1:47 pm
A(BCDE) = A(ACD) - A(ABE)

A(ACD) = [(SQRT3)/4] * (SIDE)^2
= [(SQRT3)/4] * 9

ACD is equilateral; every angle is 60.
That makes ABE 30-60-90 triangle

AB = side opposite to 30 degrees = 1
we need BE to find the area
BE = side opposite to 60 = (SQRT3)*1

A(ABE) = HALF * AB * BE
= HALF * 1 * [(SQRT3)*]

After solving A(ACD) - A(ABE), you get 'B'
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