1、A circle that rolls around another circle; generates an epicycloid or '.
繞著另一個圓圈滾轉的圓圈；產生外擺線或內擺線。

2、Construct rotating nephroid and three-cusped epicycloid while remaining orthogonal to each other.
作旋轉的腎臟線和旋轉的三瓣外擺線，且彼此維持正交。

3、The envelope of moving line on the hypocycloid plane may be an epicycloid or cardioid and the…
擺線逆運動中與動切線成定角的直線，其包絡也是圓周漸開線。