[填空题]
Express the following angles in radians: (a) q w x6h0,d. c:zayc*0bnrpy,k,, u mth3ovac4 gw)y 0)i0 $^{\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) $rad$