what are coterminal angles?
Two angles are Coterminal angles if they are drawn in the standard position (i.e. vertex of the angle is at origin and its initial side on the positive x-axis) and have terminal sides in the same location.
So the coterminal angle can be obtained by adding or subtracting n*360 degree to the measure of an angle ( n is any integer).
e.g. if we want to find the coterminal angle of 50 degree , the we can add 360 or 720 or any multiple of 360 to it.
i.e. 50 ,410 and 770 are coterminal angles.