The formulas to calculate coterminal angles are:
Positive Coterminal Angle = Angle + 360
Negative Coterminal Angle = Angle - 360
A coterminal angle is an angle that ends at the same geometric point on the coordinate plane as another angle. Since the coordinate circle has a total rotation of 360 degrees, adding or subtracting 360 degrees to the angle yields a coterminal angle.
Let's assume the following value:
Using the formulas:
Positive Coterminal Angle = 45 + 360 = 405°
Negative Coterminal Angle = 45 - 360 = -315°
The Positive Coterminal Angle is 405° and the Negative Coterminal Angle is -315°.