Returns an angle in radians of a line defined by two endpoints
(angle pt1 pt2)
An angle, in radians.
The angle is measured from the X axis of the current construction plane, in radians, with angles increasing in the counterclockwise direction. If 3D points are supplied, they are projected onto the current construction plane.
Command: (angle '(1.0 1.0) '(1.0 4.0))
Command: (angle '(5.0 1.33) '(2.4 1.33))
topic in the AutoLISP Developer's Guide.The