Find the derivative of y=(sinx/(1+cosx))^2.

I used the chain rule, but the second part involved the quotient rule which gives a very complicated expression that u do not know how to simplify. Could you please give me a detailed step by step solution for the simplifying part?

Thanks

5 answers

2(sinx/(1+cosx))d/dx (sinx/(1+cosx))

let y = sinx/(1+cosx)
dy/dx=[(1+cos)cos + sin cos ]/(1+cos)^2

= cos[ 1+cos + sin]/ (1+cos)^2

so put that back in

2(sin/(1+cos))*cos[1+cos+sin]/ (1+cos)^2

2 sin cos(1+cos+sin)/(1+cos)^3

I do not see any simplification either.
I think you did the quotient rule wrong. Should be minus not plus
Wait sorry, you just expanded. But shouldn't it be sin times sin? Not sin times cos? Since derivative of the 1+cos is -sin and the numerator is a sin?
So the answer is supposed to be sin(2x)/(1+cosx)^3 but I was wondering for the numerator why the distributive law doesn't apply when we would multiply the derivative of the outside with the inside?
I think you've both gone stray. See

http://www.wolframalpha.com/input/?i=derivative+%28sinx%2F%281%2Bcosx%29%29

and

http://www.wolframalpha.com/input/?i=derivative+%28sinx%2F%281%2Bcosx%29%29^2
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