# Homework Help: Trigo Help here plssss

1. Oct 11, 2011

### nephi37

find the derivatives

of differentiation of trigonometric functions

1. y=cos(3x^2+8x-2)

2. y=tan^3 2x

3. y=sin5x sin^5 x

4. y=Square root of 4sin^2x+9cos^2x

i cant understand trigonometric functions

2. Oct 11, 2011

### SammyS

Staff Emeritus
Welcome to PF.

Show us what you've tried.

Where are you stuck?

3. Oct 11, 2011

### nephi37

thank you summy

our teacher didn't teach us.. and dont have any idea to solve this..

Can u help me please, at least 2 of them :)

thank you very much

4. Oct 11, 2011

### SammyS

Staff Emeritus
The derivative of cos(x) is -sin(x) .

Do you know the chain rule?

5. Oct 11, 2011

### nephi37

i dont have any background with that sammy

can u help me with number 3 and number 4

6. Oct 11, 2011

### HallsofIvy

Excuse me? You have never been taught anything about derivatives of trig functions yet you are given an assignment like this? You should complain to your teacher's superior.

7. Oct 11, 2011

### nephi37

yes. she didn't taught us.. because she will discuss it to us tomorrow..

8. Oct 11, 2011

### nephi37

help plssss..

but i cant get the logic..

9. Oct 11, 2011

### SammyS

Staff Emeritus
Do you know the chain rule.

Can you find the derivative of

(3x2+8x-2)1/2 ?

10. Oct 11, 2011

### Hootenanny

Staff Emeritus
This thread is locked as a result of nephi37's refusal to follow our guidelines and provide an attempted solution.