Angular values returned by most AutoLISP functions and those stored in a drawing are expressed in radians, while angular input is commonly provided in degrees or another angular format than radians.
You can convert angular values directly with a combination of math functions, or use the angtos and angtof functions. The angtos function converts an angular value expressed in radians to degrees or one of the other supported angular formats. This function returns a string value. If you need a real (or floating point) value, you can use the atof function to convert the string value that is returned by angtos.
(setq half-PI (/ PI 2)) 1.5708 (setq angstr (angtos half-PI 0 2)) "90.00" (setq deg (atof angstr)) 90.0
(setq angstr (angtos 1.5708 1 6)) "90d0'0.76\"" (setq rad (angtof angstr 1)) 1.5708
(Radians / PI) * 180 = Degrees
; Convert value in radians to degrees (defun Radian->Degrees (nbrOfRadians) (* 180.0 (/ nbrOfRadians pi)) ) RADIAN->DEGREES (Radian->Degrees PI) 180.0
(Degrees / 180) * PI = Degrees
; Convert value in degrees to radians (defun Degrees->Radians (numberOfDegrees) (* pi (/ numberOfDegrees 180.0)) ) DEGREES->RADIANS (Degrees->Radians 180.0) 3.14159