Visualizing the Derivative of cos(x)

① This GeoGebra example dynamically demonstrates the derivative of the cosine function f(x)=cos(x), showing that its derivative graph is exactly -sin(x). ② The core mathematical concept is the geometric meaning of the derivative—the slope of the tangent line at each point on the curve—along with the differentiation rule for basic trigonometric functions. ③ Construction highlights: the Derivative command generates the derivative function f', the Line and Slope commands construct a tangent line at a moving point P and measure its slope, while points L, Q and text objects label key features, creating an interactive exploration environment. ④ It is suitable for high school or early college students learning calculus, serving as a classroom demonstration or self-study tool to bridge geometric intuition and symbolic differentiation.