I want check my answer please >

• December 7th 2009, 04:41 AM
r-soy
I want check my answer please >
Hi

I want check my answer please >

look on Attachments
• December 7th 2009, 08:07 AM
kjchauhan
L.H.S.

$=\frac{\cos^2 z-3\cos z+2}{\sin^2 z}$

$=\frac{(1-\cos z)(2-\cos z)}{(1-\cos^2 z)}$

$=\frac{(1-\cos z)(2-\cos z)}{(1-\cos z)(1+\cos z)}$

$=\frac{(2-\cos z)}{(1+\cos z)}$

=R.H.S.
• December 7th 2009, 11:17 AM
r-soy
thanks , but can explain this steps specially the first one
• December 8th 2009, 02:02 AM
mr fantastic
Quote:

Originally Posted by r-soy
thanks , but can explain this steps specially the first one

The numerator has been factorised, the denominator has been re-written using the Pythagorean identity.