So the derivative can be viewed as a slope of the tangent line. So for example, at this point right over here, it looks like the slope of our tangent line should be zero. So our derivative function should be zero at that x value. 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.