I am using the following formula to calculate the position of a point after rotation in my web application.
x' = xcos(0) - ysin(0) y' = xsin(0) + ycos(0)
But where on a graph is zero degrees in Mathematics? In the following image can you tell me where zero degrees is(is it at Point A or Point B?) If it turns out that zero degrees is at point B then I will need to add 90 degrees to all my degree values in order to use the above function, correct?