A point is attached to a circle of radius [math]r[/math], then that circle is rolled around the outside of a fixed circle of radius [math]R[/math]. The path traced out by the point is called an [b]epitrochoid[/b]. The point may be any distance [math]d[/math] from the center of the exterior circle. [br][br]If the circle with the attached point is rolled around the inside of the fixed circle, then the path of the point is called a [b]hypotrochoid.[/b]

[br][i]This applet was developed for use with [url=https://www.pearson.com/en-us/subject-catalog/p/interactive-calculus-early-transcendentals-single-variable/P200000009666]Interactive Calculus[/url], published by Pearson.[/i]