Descriptive Geometry/General method of rotation

'''To rotate an object:  Rotation in various views:'''
 * 1) Find a line axis: if rotating a point or a line, the subject cannot be incident with the axis (the point cannot be on the axis)
 * 2)  Find the center of rotation: it is the line of axis in point view
 * 3) Find the path of rotation: The plane of rotation is perpendicular to the line axis. When viewing the plane of rotation in true shape, the path of rotation is a circular one. The radius of rotation is the distance between the subject and the center of rotation.


 * 1) Viewing the line in point view: construct the circular path directly
 * 2) Viewing the line in oblique views: Find the line in true length and point view, then apply the construction above