How do I integrate sinx.cos3x
Imunable to reach the final answer: 3/2cos^2(x) - cos^4(x) + C
Wolfram|Alpha
Be sure to click on Show Steps. (And you'll need to show that the two answers are equivalent).
If you have to use integration by parts (and it has to be used twice), please show all your working and say where you get stuck.