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Find expressions for (sin t/2)2 and (cos t/2)2 from the Pythagorean theorem and the cosine addition theorem. Solution:The Pythagorian theorem is the statement (sin x)2 + (cos x)2 = 1. (or we can interpret it to be that statement). If we apply this equation for and also use the cosine addition theorem: cos (u + v) = (cos u)(cos v) - (sin u)(sin v). for , we get and we can add and subtract these equations from one another to get: |