Question

Convert the complex number z = 4 - 10i from rectangular form to polar form.​

Answer 1

ANSWER

$r = 2 \sqrt{29} ( \cos(292 \degree) + \sin(292 \degree))$

EXPLANATION

The polar form of a complex number ,

$z = x + yi$

is given by:

$z = r( \cos( \theta) + i \sin( \theta) )$

where

$r = \sqrt{ {x}^{2} + {y}^{2} }$

The given complex number is:

$z = 4 - 10i$

$r = \sqrt{ {4}^{2} + {( - 10)}^{2} }$

$r = \sqrt{16 + 100}$

$r = \sqrt{116} = 2 \sqrt{29}$

And

$\theta= \tan^{ - 1}(\frac{ y}{x} )$

$\theta= \tan^{ - 1}(\frac{ - 10}{4} )$

$\theta= 292 \degree$

Hence the polar form is :

$r = 2 \sqrt{29} ( \cos(292 \degree) + \sin(292 \degree))$