Now considerthe angle 390 o. We can think of this angleas a full rotation(360o), plus an additional30 degrees.
Noticethat 390olooksthe sameas 30o. Formally, we say that the anglessharethe sameterminalside.
Thereforewe call the anglesco-terminal.Not only are thesetwo anglesco-terminal,but thereare infinitely
manyanglesthat are co-terminalwith thesetwo angles.For example,if we rotateanother 360 o, we get the
angle 750 o. Or, if we createthe anglein the negativedirection(clockwise),we get the angle-330o. Because
we can rotatein eitherdirection,and we can rotateas manytimesas we want,we can keepgenerating
anglesthat are co-terminalwith 30o.
Example3.Whichanglesare co-terminalwith 45
o
?
a. -45o b. 405o c. -315o d. 135o