Chapter 6 - Section 6.5 - Complex Numbers in Polar Form; DeMoivre's Theorem - Exercise Set - Page 768: 89

Please see below.

By using the identity $e^{i \theta }= \cos \theta + i \sin \theta$, we have$$-e^{- \pi i}=- ( \cos (- \pi ) + i \sin (-\pi ) )=1.$$Now, we plot the complex number $z=1$ the same way we plot $(1,0)$ in the rectangular coordinate system.