The constants *pi*,*pi/2*,*2pi*,*3/2pi* are defined. The functions to manipulate angles include:3.2
(rad->deg x) // convert radians to degrees (deg->rad x) // convert degree to radians (fmod num x) // calculate num mod x (ang-pi+pi o) //given o in [0,2pi] returns the associate angle in (-pi,pi] (ang-bet-2pi o o1) // angle between o to o1, where o,o1 in [0,2pi) (ang-dir-2pi o o1) // directed angle from o to o1, where o,o1 in [0, 2pi]