# Integrating Trigonometric functions (part 5)

This will be about integrating product of trigonometric functions with no powers involved for example,

or .

The simple trick here is to use the product to sum to formulas that can be found here.
For convenience, I’ll insert them here.

So very conveniently,

.
Now you see the usefulness of the product to sum formula! Better learn how to find them!

For trigonometric functions with powers involved, you can refer to part 1 to part 5.