What is the general formula to convert radians to degrees and vice versa?

see explanation
##color(blue)( to convert radians to degrees)##
( angle in radians) ## xx 180/pi ##
example: convert ## pi/2 color(black)( radians to degrees )##
angle in degrees ##= cancel(pi)/2 xx 180/cancel(pi) =180/2 = 90^@##
##color(red)( to convert degrees to radians) ##
(angle in degrees)## xx pi/180 ##
example : convert 90 to radians
angle in radians = ##cancel (90) xx pi/cancel(180) =pi/2 ##