# Homework Help: Major h.w help needed tri functions derivatives =\

1. Jun 27, 2007

### math_student03

Hey guys having major trouble with these 2 questions, i have a screen shot of the questions and my work , much easier to understand then me typing it in here. thanks soo much for helping !

http://img204.imageshack.us/my.php?image=img050lc1.jpg

2. Jun 27, 2007

### cipher_42

You have the right idea, but you just need to be watch out for a few small things.

First of all:
Remember the Chain Rule:
$$\frac{d}{dx}(sin(2x)) = 2cos(2x)$$

Secondly:
Be careful with your minus signs, especially with going from step 2 to step 3.

Finally:
Once you get all that out of the way, go through your trig identities and see if you can't simplify it any (http://www.sosmath.com/trig/Trig5/trig5/trig5.html if you need a good list of them).

- Jason

3. Jun 27, 2007

### Integral

Staff Emeritus
You have an error in the derivitave of sin(2x) and cos(2x). Use the chain rule, you are missing a factor of 2. Continue.

4. Jun 27, 2007

### math_student03

ok so basically for my second line i was only missing a 2 for dsin(2x)/dx and dcos(2x)/dx then i can go ahead and simplift using tri propertys? did i mix something up cause i dont see any that are obvious

and secondly, did anyone check out the second question i had on that page, did i do the first and second derivative right?

5. Jun 27, 2007

### happyg1

The second one matches what I got.
CC