Let's just apply the quotient rule right over here. So this derivative is going to be equal to, it's going to be equal to the derivative of the top. Well, what's the derivative of one with respect to x? Well, that's just zero times the function on the bottom. So times cosine of x, cosine of x, minus, minus the function on the top, well, that's just one, times the derivative on the bottom. Well, the derivative of the bottom is, derivative of cosine of x is negative sine of x. So we could put the sine of x there, but it's negative sine of x, so you have a minus and there would be a negative, so we could just make that a positive.