# How do you find abs( 4-8i )?

Aug 18, 2016

$4 \sqrt{5}$

#### Explanation:

Given the complex number 4 - 8 i =(4 ,-8). If we plot (4 ,-8) then the distance( r ) from the origin to the point can be calculated using $\textcolor{b l u e}{\text{Pythagoras' theorem}}$

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

here x = 4 and y = - 8

$\Rightarrow r = | 4 - 8 i | = \sqrt{{4}^{2} + {\left(- 8\right)}^{2}} = \sqrt{80} = 4 \sqrt{5}$