Now, so the chain rule tells us that this derivative is going to be the derivative of our whole function with respect or the derivative of this outer function, x squared, the derivative of x squared, the derivative of this outer function with respect to sine of x. So that's going to be 2 sine of x. So we could view it as the derivative of the outer function with respect to the inner, 2 sine of x. We could just treat sine of x like it's kind of an x. And it would have been just 2x. But instead, it's a sine of x. So we say 2 sine of x times the derivative of sine of x with respect to x.