those docs are essentially nonsense - rotation as used there has no intrinsic “zero orientation” (ie, you can imagine zero as pointing to wherever you like, and it makes no difference, it still equals “no rotation” – rotation is a relative angle, not an absolute angle)
but compare it against some actual trig calculations and you’ll find the difference…
the “math convention” is that zero is along the positive x-axis, proceeding towards the positive y-axis. (so normally it would proceed counter-clockwise, but in corona the y-axis is inverted so it appears to proceed clockwise)
thus, the “math convention” answer to OP’s question would look something like:
xprime = x + radius \* math.cos(theta) yprime = y + radius \* math.sin(theta)
swapping cos/sin for y/x causes a 90 degree rotation and reflection about the y axis (left for reader to prove to themselves) which recreates the “clock orientation” system described in the docs. no problem, trig doesn’t care, still valid, but it looks “weird” to math people. (just take care to use same convention throughout your code!)