1. ## sin ratio

is sin alpha = sin (2pi + alpha) a tried-and-proven sine relation?

2. Originally Posted by furor celtica
is sin alpha = sin (2pi + alpha) a tried-and-proven sine relation?
Yes it is.

Look at the unit circle. If you add $2\pi$ radians to an angle (measured in radians), then the angle is exactly the same.

Thus the vertical distance, the sine of the angles, is exactly the same.

3. oh, true, thats obvious. thanks