# identity

• July 20th 2009, 02:58 AM
z1llch
identity
proving identity
$\frac {(1 + cosx + sinx)}{( 1 + cosx - sinx)}$= $\frac{ cos x (1 + sin x)} { (1 - sin^2 x)}
$

sorry my mistake.
• July 20th 2009, 03:21 AM
yeongil
I assume that you mean this:
$\frac{1 + \cos x + \sin x}{1 - \cos x + \sin x} = \frac{\cos x(1 + \sin x)}{1 - \sin^2 x}$

(Either learn LaTex or use parentheses properly, please!)

First of all, the right side is not simplified:
$\frac{\cos x(1 + \sin x)}{1 - \sin^2 x}$
\begin{aligned}
&= \frac{\cos x(1 + \sin x)}{\cos^2 x} \\
&= \frac{1 + \sin x}{\cos x}
\end{aligned}

If you do this, then this problem is the exact same one I solved earlier for arze in this thread: http://www.mathhelpforum.com/math-he...255-prove.html.

01
• July 20th 2009, 03:27 AM
z1llch
did tried to use conjugate. but couldnt simplify it..