Q5 of 25 Page 3

Express 2 sin 3x cos x as the sum or difference of sines and cosines.

We know, 2 sin A cos B = sin (A + B) + sin (A – B)


2 sin 3x cos x = sin (3x + x) + sin (3x – x)


= sin (4x) + sin (2x)


= sin 4x + sin 2x


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