Answer
$$c^2=a^2+b^2-2ab \cdot\cos{C} \\
b^2=a^2+c^2-2ac \cdot\cos{B}\\
a^2=b^2+c^2-2bc\cdot \cos{A} \\
$$
Work Step by Step
$$c^2=a^2+b^2-2ab \cdot\cos \ C $$
It can also be represented as:
$$a^2=b^2+c^2-2bc\cdot\cos \ A \\
b^2=a^2+c^2-2ac \cdot\cos \ B$$
