You can select a pline and get the segment I thinks its V1 - V2, now where is it. I know I have often used it.

`; Pline segment with angle and length`

(defun c:plseg()

(setq plent (entsel "\nSelect Pline "))

(setvar "osmode" 0)

(setq

pick (cadr plent)

plObj (vlax-ename->vla-object (car plent))

pick2 (vlax-curve-getclosestpointto plobj pick)

param (vlax-curve-getparamatpoint plObj pick2)

segment (fix param)

co-ord (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget (car plent)))))

(setq pt1 (nth segment co-ord))

(setq pt2 (nth (+ segment 1) co-ord))

(if (= pt2 nil)(setq pt2 (nth 0 co-ord)))

(setq len (distance pt1 pt2))

(setq ang (angle pt1 pt2))

(alert (strcat "angle is " (rtos (/ (* ang 180.0) pi) 2 2) " Length is " (rtos len 2 3)))

)