If you're talking about a unit circle (since you mention quadrants and rotation), sin(theta) = sin(theta + 2pi). Always.
The equation for the unit circle is x^2 + y^2 = 1.
If you're talking about the graph of a sine wave, the equation is y = sin(x). For this case, sin(x) = sin(x + 2pi).
The equation for the unit circle is x^2 + y^2 = 1.
If you're talking about the graph of a sine wave, the equation is y = sin(x). For this case, sin(x) = sin(x + 2pi).
