## anonymous one year ago Which of the following is a form of the law of cosines? A) a^2=b^2+c^2+2bc*cos A B) a^2=b^2-c^2+2bc*cos A C) b=a^2+c^2-2ac*cos B D) b^2=a^2+c^2-2ac*cos B

1. UsukiDoll

Law of cosines looks like this $cosA = \frac{b^2+c^2-a^2}{2bc}$ $cosB = \frac{a^2+c^2-b^2}{2ac}$ $cosC=\frac{a^2+b^2-c^2}{2ab}$ to have $a^2$ or $b^2$ by itself we have to manipulate this a bit.

2. UsukiDoll

forgot the $c^2$ case , but based on the choices you're given, I don't think you need it.

3. anonymous