Answer
A and B are perpendicular to each other
Work Step by Step
$|A+B|$=$|C|$
$\implies$$\sqrt {a^{2}+b^{2}+2abcos(\theta)}$ = $|C|$ = $\sqrt {a^{2}+b^{2}}$
$\therefore$ $cos(\theta) = 0$ or $\theta = 90^{\circ}$
so, $A$ and $B$ are perpendicular to each other
