[填空题]
Express the following angl*xclu0x*n cbroio yj :,d/2i :es in radians: (a) 308 mflvog ao (yst s3kfo8(e5.1 $^{\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) $rad$