Question

Express the complex number in trigonometric form.

-2i

Answer 1

\[a +bi = r(\cos \theta + i \sin \theta)\]
\[r = \sqrt{a^2+b^2}\]
For this example ,
a = 0
b = -2

---> r = 2
---> cos theta = 0 , sin theta = -1
---> theta = 3pi/2