**READ** the instructions on the *right* and **INTERACT** with the GeoGebra applet *below*.

Click on the blue icon (upper right) to reset the diagram.

- Look at the graphed function. Move the blue point
on the slider. How does the circle move? What changes in the function?*h* - Reset the diagram. Move the green point
on the slider. How does the circle move? What changes in the function?*k* - Reset the diagram. Move the red point
on the slider. How does the circle change? What changes in the function?*r* - Create a circle with a radius of 3 and its center is at (2,−3). What is the equation of this circle?

January 2006, Steven Lapinski. Applet created with GeoGebra.