Question 19 5 pts Evaluate the integral: f sin x sin 3x dx O cos 5x + = cos 3x + +cos x + C O cos x - 2cos3 x + $ cos 5x + 2 cos2 x + C O cosx + = cost x - - cos 5x + 2 cos2 x + C O -cos 5x - - cos 3x + 1cos x + C Question 20 5 pts Evaluate: f 15x29 cos x 15 dx O x15 sin a 15 - cos x 15 + C O x15 sin a 15 + cos x 15 + C O x29 sin a 15 + cos x 15 + C O al sin a 14 + cos 2 14 + C