Answer
$15^{\circ}$
Work Step by Step
To find the value of $\theta$, we need to substitute the value of $x=3$ in the equation and solve;
$\theta=\tan^{-1}(\frac{x}{x^{2}+2})$
$\theta=\tan^{-1}(\frac{3}{3^{2}+2})$
$\theta=\tan^{-1}(\frac{3}{9+2})$
$\theta=\tan^{-1}(\frac{3}{11})$
$\theta=15.3\approx15^{\circ}$
