Let the original coordinates be x 1 and y 1 and the rotation angle a be counterclockwise, then the new coordinates are
x2 = x 1*cos(a)? - y 1*sin(a)
y2 = x 1 * sin(a)+y 1 * cos(a)
For example:
x 1 = 3; y 1 = 4;
a = 15 * pi/ 180;
y2? =? x 1*sin(a)? +? y 1*cos(a)
x2? =? x 1*cos(a)? -? y 1*sin(a)