[填空题]
Express the following angles in radians: (;ivjmiiukf/j u w+kxd9*k7 .3a) 301s2u 0qv58ih3yxw n+lt d5aju $^{\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) $rad$