Question

Represent the following complex number in trigonometric form:
$\sin \alpha -i\cos \alpha$

Answer 1

$\sin \alpha -i\cos \alpha$

$⟹\cos (90-\alpha )-i\sin (90-\alpha )$

$⟹\cos (-90+\alpha )-i\sin (-90+\alpha )$

$⟹e^{i(\alpha -90)}$