Definition:Hypotrochoid

Definition
Let a circle $C_1$ roll around the inside of another (larger) circle $C_2$.

Consider a point $P$ on the line of a radius of $C_1$ at a distance $d$ from the center of $C_1$.

The curve traced out by $P$ is called an hypotrochoid.

Hypocycloid
The special case where $d = b$ is usually treated separately:

Also see

 * Equation of Hypotrochoid


 * Definition:Epitrochoid
 * Definition:Trochoid