4 triangles

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4 triangles

by pappueshwar » Sat Mar 24, 2012 2:43 am
A rectangle is inscribed with congruent isosceles triangles, a portion of which shown. The verticals of the triangles are the height of the rectangle. If the bases of four triangles span the base of the rectangle, and the ratio of the base to the height of each of the triangles is 4:7, the area of the rectangle, in terms of base b of a triangle, is

Image

a) 7/4 b

B) 8b

C) 4 (b+7) ^ 2

D)7 b ^2

E) 8 b^2

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by rperezgmat » Sat Mar 24, 2012 10:39 am
Answer is D.

Make b=4
Height h=7
There are 4 triangles.
Therefore, the base of the rectangle is 16. The rectangle must be 16(7) if b=4.

Checking all the AC's given, only D works when substituting 4 for b.
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