# Homework Help: Trigonometric identity

1. Oct 13, 2012

### Feodalherren

1. The problem statement, all variables and given/known data

2. Relevant equations

Any trig formulas

3. The attempt at a solution

The yellow paper is me switching everything to sin and cos to see if that helps but it doesn't. I'm completely stuck here.

2. Oct 13, 2012

### Feodalherren

Oh yeah, it's problem fifty. Forgot to say that :).

3. Oct 13, 2012

### SammyS

Staff Emeritus
What yellow paper ?

4. Oct 13, 2012

### Feodalherren

You can't see the images?

5. Oct 14, 2012

### SammyS

Staff Emeritus
Not at all.

6. Oct 14, 2012

### Feodalherren

http://img839.imageshack.us/img839/2928/one0001.jpg [Broken]

Does that work?

Last edited by a moderator: May 6, 2017
7. Oct 14, 2012

### Staff: Mentor

at the step where you combine the two fractions you sucked in the minus sign and then lost a minus as you multiplied the second term with 1-tan(theta). Do you see that?

you should instead have: 4 tan(theta) / ( 1 - tan^2(theta) )

8. Oct 14, 2012

### Feodalherren

Got it. Thank you!