PROve

Asked by  | 12th Sep, 2008, 07:54: PM

Expert Answer:

we know that 2sinA sinB = cos(A-B) - cos(A+B)

so cos(3π/4 + x) - cos(3π/4 - x) = - 2 sin x sin3π/4 = -2sin x (1/2) = -2 sin x

Answered by  | 12th Sep, 2008, 09:08: PM

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