We've now figured out the derivative. It's going to be this times this. So let's see, that's going to be negative three, negative three times sine of x times cosine squared of x. And I know that was kind of a long way of saying it. I'm trying to explain the chain rule at the same time. But once you get the hang of it, you're just going to say, all right, well let me take the derivative of the outside of something to the third power with respect to the inside. Let me just treat that cosine of x like as if it was an x.