Rolling a coin around a coin

Curves, Plane GeometryThe red circle rolls on the outside of the black circle of radius 1. (The blue point shows how it rolls.) An invisible point at distance q from the center of the black circle is attached to the red circle, tracing out a path as the red circle rolls; such curves are called epitrochoids. When the circles have the same radius, you can see that the blue point is oriented in the same direction after half a revolution. Therefore a coin rolling completely around another coin of the same size goes through two complete revolutionsComponente Curricular::Educação Superior::Ciências Exatas e da Terra::Matemátic