The diameter and the circumference of a circle correlate.

圆的直径与圆周有相互。

Please move counterclockwise in a circle!

逆时针做圆周运动。

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

摆线逆运动中与动切线成角的直线,其包络是圆周渐开线.

Definition : A strophoid of a circle with the pole O at the centre of the circle and the fixed point P on the circumference of the circle.

在圆上的环索线，以圆心为极，圆周上的一为固，所作出的图形！