### Possible Answer

It's because there is a trigonometric identity stating that sin(2x) = 2sin(x)cos(x). So with your situation, sin(2x)cos(2x) would equal (1/2)sin(4x).Take the derivative of that and you get 2cos(4x). - read more

How do you take the derivative of the problem mentioned above? please show steps - read more

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