And you can see that it makes sense not just at the points we tried, but even in the trends. If you look at sine of x here, the slope is one, but then it becomes less and less and less positive all the way until it becomes zero. Cosine of x, the value of the function, is one, and it becomes less and less positive all the way until it equals zero. And you could keep doing that type of analysis to feel good about it. In another video, we're going to prove this more rigorously. So now let's think about cosine of x. So cosine of x, right over here, the slope of the tangent line looks like it is zero.