Drawing 4-circle with 5-compass
How to draw a circle of radius 4 using a compass stuck on 5 inches...
By dragging the "transform" slider you can see how the circle transforms into a cone with a final state of 1/4 of the original circle overlapping on the surface of the cone. In this final state the radius of the base circle is 4 (it coincides with the thin red circle). Also try dragging the "Finetune" and "Rotate".