# math

A parallelogram has diagonals of length 10 cm and 17 cm. An angle between them is 125°. Find:
a. the area of the parallelogram
b. the dimensions of the parallelogram.

I have found a. to be:
1/2 * 10 * 17 *sin(125)
= 69.63cm^2

Just need help with part b

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1. The diagonals of a parallelogram cut it into 4 triangles of equal area,
so one of them = (1/2)(5)(8.5)sin125° = 17.407
so the whole parallelogram = 4(17.04) = 69.63 cm^2, (you had that.)
for the sides, I would use the cosine law on one of the triangles
longside^2 = 5^2 + 8.5^2 - 2(5)(8.5)cos125°
longside = appr 12.09 cm

shortside^2 = 5^2 + 8.5^2 - 2(5)(8.5)cos55°
.... take over

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posted by Reiny
2. thank you!

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