Question

The law of cisines is a +b+c -abcosC=c find the value of2abcosC

Answer 1

{a^2 + b^2 - c^2} is the final answer!

Answer 2

The law of cosines says
`c^2 = a^2 + b^2 - 2abc\cos C`.

Given this, we can add
`2ab\cos C` to the both sides and subtract
`c^2` from the both sides to get the equation
`2ab\cos C = a^2 + b^2 - c^2`.

Thus, the value of
`2ab\cos C` is
`\boxed{a^2 + b^2 - c^2}`.