# Pretty difficult trig proof (identity)

1. Aug 25, 2011

### iRaid

1. The problem statement, all variables and given/known data
$\frac{sin\theta}{1-cos\theta} - \frac{cot\theta}{1+cos\theta} = \frac{1-cos^{3}\theta}{sin^{3}\theta}$

2. Relevant equations
Trig identities..

3. The attempt at a solution
Basically I got to:
$\frac{sin\theta+(cos^{2}\theta)(sin\theta)}{sin^{2}\theta}$
1. The problem statement, all variables and given/known data

Is that right up to there, I think not because I cant get passed this lol.

2. Relevant equations

3. The attempt at a solution

2. Aug 25, 2011

### SammyS

Staff Emeritus
That doesn't look right.

Show how you got your result so we can help you.

3. Aug 25, 2011

### PeterO

You did notice the cot function did you - or did you misread it as cos?

4. Aug 25, 2011

### PeterO

I don't think you were supposed to solve the question for the Original Poster!!!!!

Last edited by a moderator: Aug 25, 2011
5. Aug 25, 2011

### Dr. Seafood

>_> Oh. Well, I hope my explanation blurb thing helps so that I'm not just blatantly giving the solution without providing any real understanding.

6. Aug 25, 2011

### Staff: Mentor

PeterO is correct. The Physics Forums rules do not permit a member to post the solution to another member's problem.

7. Aug 26, 2011

### iRaid

OK, I attached the rest of my work..

#### Attached Files:

• ###### IMAG0031.jpg
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8. Aug 26, 2011

### PeterO

In your 5th line, when you took out a factor of sin(theta) in the numerator, it was not a common factor, as it was in the denominator of a couple of the terms.

9. Aug 26, 2011

### iRaid

I see now thanks, I got it. Stupid mistakes.