Similarly, over here, it looks like the derivative is zero. The slope of the tangent line would be zero. So whatever our derivative function is at that x value, it should be equal to zero. If we look right over here on sine of x, it looks like the slope of the tangent line would be pretty close to one. If that is the case, then in our derivative function, when x is equal to zero, that derivative function should be equal to one. Similarly, over here, it looks like the slope of the tangent line is negative one, which tells us that the derivative function should be hitting the value of negative one at that x value. So you're probably seeing something interesting emerge.