EXAMPLES XIII 191 



(21) fe- 3 * cos 2x dx (22) (e* sin 2 x dx 



(23) (e cos 8 x dx (24) fe 3 * sin 4 x dx 



(25) U 3 * cos 4 x dx (26) le- 2 * sin 2 x dx 



(27) U- 3 * cos 2 x dx (28) ftan- 1 x dx 



(29) U 2 tan- 1 x dx (30) fsin- 1 a; dx 





