(a) Beginning with the identity cos 2u cos2 u sin2 u,
Chapter 8, Problem 34(choose chapter or problem)
(a) Beginning with the identity cos 2u cos2 u sin2 u, prove that cos 2u 1 2 sin2 u. (b) Using the result in part (a), prove that sin2 u (1 cos 2u)/2. (c) Derive the formula for sin(s/2) as follows: using the identity in part (b), replace u with s/2, and then take square roots.
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