Interactive Circle Equation Intro: Constructing a Circle via Input Boxes and Poi

① This example demonstrates how to dynamically construct a circle using user-specified center coordinates and radius, with its standard equation displayed in real time. ② The core mathematical concept is the analytic geometry definition of a circle: the set of points at a fixed distance (radius) from a fixed point (center), expressed by the standard equation (x-h)²+(y-k)²=r². ③ Construction details: from the summary, it uses Textfield for entering h, k, and r, Point to create the center C, Segment to draw the radius, InputBox to bind user inputs, and the equation object eq1 to generate the circle's equation text, with auxiliary objects A and f for display. ④ Suitable for middle school advanced or high school introductory analytic geometry, and for GeoGebra classroom demonstrations to help students intuitively grasp how parameter changes affect the circle's position and size.