So let me make it clear. That's what we're taking the derivative of with respect to sine of x. With respect to sine of x. And then we're multiplying that times the derivative of sine of x with respect to x. And this is where it might start making a little bit of intuition. You can't really treat these differentials, this d whatever, this dx, this d sine of x, as a number. And the notation makes it look like a fraction, because intuitively that's what we're doing.