# Thread: Stuck on simple integration by parts

1. ## Stuck on simple integration by parts

How do I integrate sinx.cos3x

Imunable to reach the final answer: 3/2cos^2(x) - cos^4(x) + C

2. Originally Posted by DeRSeD
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.