## anonymous 3 years ago Find cos θ if sin θ = -5/13 and tan θ > 0.

1. myininaya

If sine is negative and tangent is positive, then cosine is ____?____ tangent=sine/cosine=negative/cosine=positive =>cosine is ___?____

2. anonymous

positive?

3. myininaya

So negative/positive is positive No...

4. anonymous

no its negative

5. myininaya

Right. You want tangent to be positive not negative

6. anonymous

positive

7. myininaya

So you need cosine to be negative in order for tangent to be positive since sine is negative.

8. myininaya

So we are in the (-,-) quadrant.

9. anonymous

yea

10. anonymous

correct

11. myininaya

|dw:1351269639105:dw| $\sin( \theta)=-5/13 \text{ is given to you}$

12. anonymous

so then use pythagorean theorem to fine cosine

13. myininaya

Find the other side using the Pythagorean thm.

14. anonymous

which would end up being -12/13

15. myininaya

the other side is 12 is what you are saying and no i thought you were looking for cosine...

16. myininaya

oops I labeled the triangle wrong a little bit.

17. anonymous

i am

18. myininaya

|dw:1351270002298:dw|

19. myininaya

And you will be correct. :)

20. anonymous

|dw:1351270017306:dw|

21. anonymous

yay

22. anonymous

thank you!!!!

23. myininaya

Right.