Question

the law of cosines is a2+b2-2abcosC=c2 find the value of 2abcosC

Answer 1

Isolating 2abCos(c) on one side of the equation and using the given values of a, b and c we can find the answer to this question as shown below:

$a^{2} + b^{2} -2ab*cos(C)=c^{2} \\ \\ 2ab *cos(C)= a^{2} + b^{2} - c^{2} \\ \\ 2ab *cos(C)=2^{2} + 2^{2}- 1^{2} \\ \\ 2ab*cos(C) = 7$

Answer 2

2ab * cos (C)= 7

hope this helps you