Inverses in Group Direct Product

Theorem
Let $\left({G \times H, \circ}\right)$ be the group direct product of the two groups $\left({G, \circ_1}\right)$ and $\left({H, \circ_2}\right)$.

If:
 * $g^{-1}$ is an inverse of $g \in \left({G, \circ_1}\right)$

and:
 * $h^{-1}$ is an inverse of $h \in \left({H, \circ_2}\right)$

then $\left({g^{-1}, h^{-1}}\right)$ is the inverse of $\left({g, h}\right) \in \left({G \times H, \circ}\right)$.