Introduction to the Cosine Function: Unit Circle and Graph

①This example dynamically demonstrates the definition of the cosine function using a point on the unit circle, linking the geometric ratio (adjacent/hypotenuse) to the algebraic graph of y = cos(x). ②Core mathematical concepts include the unit circle, radian measure, the cosine function's periodicity, symmetry, and range, as well as the relationship between angle and coordinate. ③Construction details: Based on the summary, objects such as k, f, b, c, A, g, a, text2, and text1 are used—likely representing the unit circle (k), the cosine graph (f), a dynamic point A with its coordinates (a), auxiliary lines (g), and text labels (text1, text2). The point A moves along the circle, updating the graph and displayed values in real time. ④This is suitable for high school or introductory college students learning trigonometry, and for teachers to illustrate the connection between the unit circle and the cosine curve in an interactive classroom setting.