law of cosines
The law of cosines states that c2 = a2 + b2 - 2ab cos C.

It allows us to calculate the third missing side when two sides and the angle in between are known.


        a2 = b2 + c2 - 2bc cos A
        b2 = c2 + a2 - 2ca cos B

Related Terms: law of sines, law of tangents

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