Answer
$13.4\ m$
Work Step by Step
The angle toward the $+x^{\prime}$ axis is $18.0^{o}$ less than before, so
$\theta^{\prime}=56.0^{o}-18.0^{o}=38.0^{o}$
The magnitude of $\vec{a}$ remains the same.
Given the magnitude and new angle (in the new coordinate system), using (3-5),
$a_{x}^{\prime}=a\cos\theta^{\prime} =(17.0m)(\cos 38.0^{o})=13.4\ m$
