# Math

In a parallelogram a diagonal of the length 20 cm is perpendicular to one of the sides. Find the longer side of parallelogram if its perimeter is 80 cm.

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asked by Sam
1. let long side = x
short side = s and is perpendicular to diag
s^2 + 400 = x^2
so s^2 = x^2 - 400
2 s + 2 x = 80
s = 40 - x
1600 - 80 x + x^2 = x^2 - 400
80 x = 2000
x = 200/8 = 100/4 = 25

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posted by Damon

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