When I'm doing problems using the double-angle formulas, like sin(2 theta) = 2(sin theta)(cos theta), I don't have to alter the given range. But when I'm doing problems using the half-angle formulas, like sin (alpha/2) = +/- square root of ([1 - cos alpha] / 2), I have to alter the given range by dividing everything by 2. Why don't I have to alter the range for the first type of problem (double-angle formulas)?
Thank you!
Thank you!