Question 1025987
I have a parallelogram, and I need to find the angles. 

The measurements I have are that the sides are 12 and 22, and the longer diagonal is 28. 
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Call the angle opposite the diagonal D.
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Use the Cosine Law:
d^2 = 12^2 + 22^2 - 2*12*22*cos(D) = 28^2
cos(D) = 156/528
D = 107.2 degs
--> 2 angles of 107.2 & 2 angles of 72.8 for a sum of 360 degs.
One angle of each triangle is 107.2.  The second angle of each is not 72.8 degs.
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28/sin(D) = 12/sin(A)
sin(A) = 12*sin(D)/28 =~ 0.409
A =~ 24.2 degs, not 72.8