The envelope of moving line on the hypocycloid plane may be an epicycloid or cardioid and the...

摆逆运切成定角的直,其包络是圆周渐开.

Construct rotating nephroid and three-cusped epicycloid while remaining orthogonal to each other.

作旋转的肾旋转的三瓣外摆，且彼此维持正交。