SOLUTION: find the area of a rectangle with length 4 and diagonal 5.

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Question 204381: find the area of a rectangle with length 4 and diagonal 5.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Start with:
A+=+L%2AW
You are given the length (L = 4) but not the width (W).
You can find the width using the Pythagorean theorem:c%5E2+=+a%5E2%2Bb%5E2 where c is the hypotenuse of the right triangle (also the diagonal of the rectangle), and a is the length of the rectangle.
b is the width (W) which is what we need to find before we can calculate the area. So...
5%5E2+=+4%5E2%2BW%5E2
25+=+16%2BW%5E2
W%5E2+=+25-16
W%5E2+=+9
W+=+3
The area is:
A+=+L%2AW Substitute L = 4 and W = 3.
A+=+4%2A3
highlight%28A+=+12%29 sq.units.