Find angles m and n.
Use the law of cosines to calculate the angels.
a2 = b2 + c2 −2bc * cos(A)
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Example:
Triangle ABC has sides: a=2, b=3, c=4
22 = 32 + 42 - 2*3*4*cos(A)
cos(A) = 32 + 42 - 22/ 2*3*4 = 0.875
Angle A = 28.955º
