SOLUTION: Derive the half angle formula for sin( u/2 ) by following the steps below. (a) Use the sum angle formula to write cos(2x) in terms of powers of sin(x) and cos(x) . (b) Use a tri

Question 431469: Derive the half angle formula for sin( u/2 ) by following the steps below.
(a) Use the sum angle formula to write cos(2x) in terms of powers of sin(x)
and cos(x) .
(b) Use a trig identity to rewrite cos(2x) in terms of just powers of sin(x):
(c) Solve the formula in part (b) in terms of sin(x), and not a power of
sin(x).
(d) Substitute x = u/2 into the formula in part (c).
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!

Replacing x with u/2,

(however you must be careful what quadrant u and u/2 are in, because it could be positive or negative).
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