I can't solve this :S

cosxsinx/tanx = 1 - sin^2x

thanks :D

Printable View

- May 17th 2011, 09:07 AMkatiethegreattrig identity help...
I can't solve this :S

cosxsinx/tanx = 1 - sin^2x

thanks :D - May 17th 2011, 09:10 AMTheEmptySet
- May 17th 2011, 09:20 AMkatiethegreat
I don't know why....but i still don't get it :/

- May 17th 2011, 09:21 AMTheEmptySet
- May 17th 2011, 09:33 AMkatiethegreat
both :/

- May 17th 2011, 09:43 AMmasters

Hi katiethegreat,

Maybe if you see it like this, it would help:

$\displaystyle \dfrac{\cos (x) \sin(x)}{\tan (x)}=$

$\displaystyle \dfrac{\cos(x) \sin(x)}{\frac{\sin (x)}{\cos (x)}}=$

$\displaystyle \dfrac{\cos (x) \sin (x)}{1} \cdot \frac{\cos (x)}{\sin (x)}=$

He just used the identity: $\displaystyle \tan (x) = \frac{\sin (x)}{\cos (x)}$

You should be able to finish now if you know $\displaystyle \sin^2(x)+\cos^2(x)=1$