1. ## fundimental identies

use the fundimental identies to find the value of the trigonomic function.
sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

1. -3/2
2. (3 square root 7)/7
3. 5/4
4. -( square root 5)/3

2. Originally Posted by wenatchee
use the fundimental identies to find the value of the trigonomic function.
sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

1. -3/2
2. (3 square root 7)/7
3. 5/4
4. -( square root 5)/3
Is your 0 supposed to represent $\displaystyle \theta$?

Make use of the Pythagorean Identity:

$\displaystyle \cos^2{\theta} + \sin^2{\theta} = 1$

$\displaystyle \left(\frac{2}{3}\right)^2 + \sin^2{\theta} = 1$

$\displaystyle \frac{4}{9} + \sin^2{\theta} = 1$

$\displaystyle \sin^2{\theta} = \frac{5}{9}$

$\displaystyle \sin{\theta} = \pm \frac{\sqrt{5}}{3}$.

Since $\displaystyle \theta$ is in Quadrant 4, we know $\displaystyle \sin{\theta}< 0$.

So $\displaystyle \sin{\theta} = -\frac{\sqrt{5}}{3}$.

3. Originally Posted by wenatchee
use the fundimental identies to find the value of the trigonomic function.
sin 0, if cos 0 = 2/3 and 0 is in quadrant IV

1. -3/2
2. (3 square root 7)/7
3. 5/4
4. -( square root 5)/3
I take it that by "0", you mean $\displaystyle \theta$.

So...

$\displaystyle \sin\theta=\sqrt{1-\cos^2\theta}$

Can you see what needs to be done?

4. Originally Posted by VonNemo19
I take it that by "0", you mean $\displaystyle \theta$.

So...

$\displaystyle \sin\theta=\sqrt{1-\cos^2\theta}$

Can you see what needs to be done?
Beat ya

5. Originally Posted by Prove It
Beat ya
You did indeed, you scoundrel! Until we meet again, Proveit!

6. ## slowly

Thanks I left my book and calculator at school and missed this whole section due to swine flu.

7. Originally Posted by wenatchee
Thanks I left my book and calculator at school and missed this whole section due to swine flu.
Where you from? In the US, I mean.

8. how do you get all the math symbols

9. malaga washington

10. You get the math symbols using LaTeX.

Go to the LaTeX help sub-forum on this site, and read through the tutorials.

11. Where in Austrailia are you from? I used to live in Sydney for about 6 months.

12. Melbourne, but I am currently living in Mildura.