Coterminal angles are non-coincident plane angles 
and 
in angle standard
position whose terminal sides coincide.
In general, given a plane angle 
measured in radians, 
is coterminal to 
if and only if 
for some positive
integer 
.
Similarly, if 
is a plane angle coterminal to a plane angle 
measured in degrees, then 
for some positive integer
. If 
, then 
and 
are coincident.
In the figure above, the non-coincident angles 
and 
are coterminal angles.
