Question

How does sin x cos pi/2 + cos x sin pi/2 simplify to cos x?

Answer 1

cos(pi/2) = 0
sin(pi/2) = 1

sin(x)*cos(pi/2) + cos(x)*sin(pi/2) = sin(x)*0 + cos(x)*1 = 0 + cos(x) = cos(x)

Answer 2

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