Answer
$2\pi; \pi$
Work Step by Step
When the central angle is $360^{\circ}$,
arc length=circumference=$2\pi r$ where $r$ is the radius of the circle. Then, in radians,
$\theta=\frac{\text{arc length}}{\text{radius}}=\frac{2\pi r}{r}\,rad=2\pi\,rad$
$360^{\circ}=2\pi \,rad\implies 180^{\circ}=\pi \,rad$
