quadrilateral

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quadrilateral

by grandh01 » Mon Aug 20, 2012 3:19 pm
In the figure above, CE = 5, BD = 8,
and the area of quadrilateral ABCD is
36. What is the area of â–³ABD ?
(A) 4
(B) 9
(C) 16
(D) 20
(E) 56

Check attachment for figure.
Thanks in advance
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by truplayer256 » Mon Aug 20, 2012 4:07 pm
I'm going to assume they want to find the area of triangle ABD? I can't quite see the end part of the question as for it is not visible.

Area of quad. ABCD = Area of triangle BDC + Area of triangle ABD

36 = (5)(8)/2 + Area of triangle ABD

36 - 20 = 16 = Area of triangle ABD.

Choose C.

Note that the Area of triangle BDC was (5)(8)/2 because 8 was the base and 5 was the height. And as every GMAT taker should know, the area of a triangle is (1/2)(base)(height).