# Integrating Trigonometric functions (part 2)

As promised, we will look at this time. It might get boring, as the method is exactly the same as as they are quite related.

Easy!

This requires double angle formula:

Here we introduce trigo identity:

Here we have a problem!

But recall we did some really similar in part 1, and notice that is the derivative () of .

So .

Finally,

Here we can apply double angle a few times to break it down before integrating.

After seeing both part 1 and part 2, you should notice some intuitive method.

Consider and .

Should n be even, we introduce the double angle formula to simplify things.
Should n be odd, we introduce the trigonometry identities and integrate. We must apply method to integrate. Just saying, .

Tell me what you think in the comments section!