Practice: Equation of Circles - Interactive Input and Dynamic Verification

① This example demonstrates how to write the standard equation of a circle given its center and radius, with interactive input fields and real-time verification. ② The core mathematical concept is the standard equation of a circle in coordinate geometry: (x-h)²+(y-k)²=r², emphasizing the geometric meaning of parameters h, k, and r. ③ Construction details: The GeoGebra commands used include Sequence to generate points on the circle, If to check whether the user's input matches the standard equation, Textfield and InputBox for user input, button1 to trigger verification, variables vars to store parameters, eq1 and eq2 for the standard and user equations, and text1 to display feedback. ④ Suitable for high school students learning coordinate geometry, useful for classroom practice or self-study to reinforce the connection between algebraic equations and geometric circles.