Try this guys; it?s interesting. A disk of radius 1 cm has a small hole at a point half way between the center and the circumference. The disk is lying inside a circle of radius at 2 cm. A pen is put through the hole in the disk, and then the disk is moved once round the inside of the circle, keeping the disk in contact with the circle without slipping, so the pen draws the curve. What is the area enclosed by the curve?