Let be the three sides of a triangle , and let
, be the angles opposite them. If ,
find
Huh.. that was long..
First thing I thought about this equation was the law of cosines. We'll use it later as expected.
Let's start of with reducing this.
As ,
Law of sines tell us that
From here we get and .
By using them,
It's simple enough now. Time to find by the law of cosines..
By the law,
We got now. By using it,