# What is the Cartesian form of (45,(-pi)/8)?

$\left(45 \cos \left(\frac{\pi}{8}\right) , - 45 \sin \left(\frac{\pi}{8}\right)\right)$
If you write this in trigonometric/exponential form, you have $45 {e}^{- i \frac{\pi}{8}}$.
$45 {e}^{- i \frac{\pi}{8}} = 45 \left(\cos \left(- \frac{\pi}{8}\right) + i \sin \left(- \frac{\pi}{8}\right)\right) = 45 \left(\cos \left(\frac{\pi}{8}\right) - i \sin \left(\frac{\pi}{8}\right)\right)$.
I don't think $\frac{\pi}{8}$ is a remarkable value so maybe we can't do better than that.