$$1rad = \left( {\frac{{180^\circ }}{\pi }} \right) \approx 57.2958^\circ \approx 57^\circ 17'45'',$$
$$1^\circ = \frac{\pi }{{180}}rad \approx 0.017453{\text{ }}rad$$
$$1' = \frac{\pi }{{180 \cdot 60}}rad \approx 0.000291{\text{ }}rad$$
$$1'' = \frac{\pi }{{180 \cdot 60 \cdot 60}}rad \approx 0.00005{\text{ }}rad$$
