So we want to figure out f prime of x, and as we will see, the chain rule is going to be very useful here. And what I'm gonna do is I'm going to first just apply the chain rule, and then maybe dig into it a little bit to make sure we draw the connection between what we're doing here and then what you might see in maybe some of your calculus textbooks that explain the chain rule. So if we have a function that is defined as essentially a composite function, notice this expression right here, we are taking something to the third power. It isn't just an x that we're taking to the third power, we are taking a cosine of x to the third power. So we're taking a function, you could view it this way, we're taking the function cosine of x, and then we're inputting it into another function that takes it to the third power. So let me put it this way. If you viewed, if you say, look, we could take an x, we put it into one function, that is, that first function is cosine of x, so first we evaluate the cosine, and so that's going to produce cosine of x, cosine of x, and then we're going to input it into a function that just takes things to the third power.