Answer
Its angle in the $xz$ plane (measured from the $+x$ $axis$) is one of these possibilities: $$ \tan ^{-1}\left(\frac{0.5 \mathrm{m} / \mathrm{s}^{2}}{-1.5 \mathrm{m} / \mathrm{s}^{2}}\right)=-18^{\circ} \text { or } 162^{\circ} $$ $\text{where we settle on the second choice since the signs of its components imply }$$\text{that it is in second quadrant.}$
Work Step by Step
Its angle in the $xz$ plane (measured from the $+x$ $axis$) is one of these possibilities: $$ \tan ^{-1}\left(\frac{0.5 \mathrm{m} / \mathrm{s}^{2}}{-1.5 \mathrm{m} / \mathrm{s}^{2}}\right)=-18^{\circ} \text { or } 162^{\circ} $$ $\text{where we settle on the second choice since the signs of its components imply }$$\text{that it is in second quadrant.}$
