Approach this question by subtracting 2π from the given angle until you reach an angle that's within the range of 0 to 2π. This method is especially useful for fractional multiples of pi.
The particular question you have here is a little easier because it's an integer multiple of pi, so a couple things are worth noting:
- Every even integer multiple of pi (e.g. -2π, 4π, 6π, 78π, 100π) will be coterminal with 0.
- Every odd integer multiple of pi (e.g. -π, 3π, 5π, 17π, 29π) will be coterminal with π .
Hope that helps. Let me know if you have any questions about this explanation.
