Answer
$r = \sqrt{13}$
Work Step by Step
The blue line represents the terminal side of $\theta$ in its standard position.
To find the distance from the origin to $(3,-2)$, we use the distance formula
$$r=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\\r=\sqrt{(3-0)^2+(-2-0)^2}=\sqrt{13}$$
