1. ## Trig Differentation

I need help to differentate these 2 questions. Thanks for your help in advance.

y = sinx/1+cosx
For this one, i tried the quotient rule and ended off with cosx + cos^2(x) + sin^2(x)/ 1+cosx^2 which is not the right answer.

y = cos(sin2x)
I tried product rule and for the wrong answer.

2. The first one is correct IF you square the entire denominator.
Then use cos^2(x) + sin^2(x)=1 AND reduce.
You need the chain rule on the second one.

3. Originally Posted by proski117
I need help to differentate these 2 questions. Thanks for your help in advance.

y = sinx/1+cosx
For this one, i tried the quotient rule and ended off with cosx + cos^2(x) + sin^2(x)/ 1+cosx^2 which is not the right answer.

y = cos(sin2x)
I tried product rule and for the wrong answer.
I used the quotient rule on number 1 and got $\frac{1+cos(x)}{(1+cos(x))^2} = \frac{1}{1+cos(x)}$

4. can you guys show me how to do the second one? i dont know what im doing wrong when using the chain rule

5. Originally Posted by proski117
can you guys show me how to do the second one? i dont know what im doing wrong when using the chain rule

y = cos(sin2x)

$y' = -sin(sin(2x)) \times 2cos(2x) = -2sin(sin(2x))cos(2x)$

note that 2cos(2x) is the derivative of sin(2x)