Is this correct?Yes, your solution is correct. Good job!

[BuBbLeS01]

1 more derivative problem!

Homework Statement

Find the derivative of...
2sinxcosx
not simplified

The Attempt at a Solution

(2cosxcosx) - (2sinxsinx)

I just want to make sure this is right

 

[rock.freak667]

yes that is correct..but you should simplify cosxcosx to $$cos^2x$$ and likewise with the sinxsinx

 

[dynamicsolo]

yes that is correct..but you should simplify cosxcosx to $$cos^2x$$ and likewise with the sinxsinx

And, when you're done, does that result look like a trig identity you've seen before? Could you have gotten the same result by using a trig identity on 2 sin x cos x first?

 

[MrSparky]

dy/dx = 2 sin x . -sin x +cos x . cos x= 2 ( cos squared - sin squared)

So yes your correct

 

[HallsofIvy]

Which, as dynamicsolo hinted, is the same as 2 cos(2x) and could have been done more simply by recognizing that 2 sin(x) cos(x)= sin(2x).