Trig. Law of Cosines
posted by ashley .
Show that any triangle with standard labeling...
a^2+b^2+c^2/2abc = cos(alpha)/a + cos(beta)/b + cos(gamma)/c
I don't get it. Can someone please help me.
Start here with the law of cosines:
a^2 = b^2 + c^2 2bc Cos A
b^2 = a^2 + c^2 2ac Cos B
c^2 = a^2 + b^2  2ab Cos C
Add the three equations. divide both sides by 2abc
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