用一个空间圆表示一个空间任意平面，用一个矢量表示一个空间任意轴，围绕这空间任意轴旋转的动态显示，得到空间圆的圆心的轨迹。-A space arbitrary axis, around the dynamic display of arbitrary axis rotation in this space, the space center of the circle track any plane with a vector represents a space with a space round.