Move the sliders of the radius (r) and the height (h) to observe the changes to the cone and the net of the cone. The slant height (s) is calculated from (r) and (h) on the sliders. Also, the ratio (r)/(s) is calculated. Notice that (r)/(s) is the same size as the sector of the circle of radius (s) in the net of the cone! Try to get (r)/(s) to be 0.5 and observe the circle sector is now a semicircle!