[填空题]
Express the following angle8c-;me i uyjb mms6-z-s imirb2 2 r,45qm k3 siaq7nt.hay6s n xtkg;-4kn radians: (a) 30 $^{\circ} $, (b) 57 $^{\circ} $, (c) 90 $^{\circ} $, (d) 360 $^{\circ} $, and (e) 420 $^{\circ} $. Give as numerical values and as fractions of $\pi$.(Round to two decimal places)
(a) $rad$ (b) $rad$ (c) $rad$ (d) $rad$ (e) $rad$
