Angle reference to a line

[Dayananda]

How can I get the angle A and B by a lisp code.

[fuccaro]

(setq A (- (angle p1 p3) (angle p1 p2)))
(setq B (+ (* 2.0 PI) (angle p1 p4) (- (angle p1 p2))))

I can not test it right now, but it should work...

[hanhphuc]

not sure if OP wants to apply dimension?

refer to RHS in the picture, 1 ,2 ,3, B= text position

 

Command: DIMANGULAR

Select arc, circle, line, or <specify vertex>:   <ENTER>

Specify angle vertex:         <--- pick p1 (center)
Specify first angle endpoint: <--- pick p2
Specify second angle endpoint: <--- pick p3 then place B

Non-associative dimension created.

 

or vb method

object.AddDim3PointAngular(AngleVertex, FirstEndPoint, SecondEndPoint, TextPoint)

(apply 'vla-AddDim3PointAngular
       (cons *modelspace*
       (mapcar ''((p) (vlax-3d-point (trans p 1 0)))
	       (list p1 p2 p3 B)
	       )
       )
)