## rudra333 Group Title a math question one year ago one year ago

1. rudra333 Group Title

$\cos ^{-1}(\sin \frac{ 11\pi }{ 6 })$

2. rudra333 Group Title

@satellite73

3. rudra333 Group Title

@satellite73 plz help

4. zugzwang Group Title

Play with the values for this one... Let $x = \cos^{-1}(\sin \frac{11\pi}{6})$and if we get the cosine of both sides, we are left with...$\cos x = \sin \frac{11\pi}{6}$perhaps it's simpler from here on in?

5. rudra333 Group Title

6. zugzwang Group Title

seems like it

7. rudra333 Group Title

@satellite73

8. zugzwang Group Title

You're right. Hang on... in general, $\cos(\frac{\pi}{2} - \theta)=\sin(\theta)$ So $\sin\frac{11\pi}{6}=\cos \left( \frac{\pi}{2}-\frac{11\pi}{6} \right)$ $=\cos \left( -\frac{8\pi}{6} \right)$ It would appear $x=-\frac{4\pi}{3}+2k\pi$ where k is any integer. But since we're talking angles, adding 360 degrees, or 2pi, would give the same angle. Consider doing that here, because that negative angle ain't pretty XD $x = -\frac{4\pi}{3}+2\pi=\frac{2\pi}{3}$

9. rudra333 Group Title

k thanks but this other one is hard $\tan(\sin ^{-1}-\frac{ 5 }{ 13 }$

10. rudra333 Group Title

)

11. zugzwang Group Title

It's a bit complicated, but think of it this way... the SINE of the angle is -5/13, so what is its TANGENT?

12. alanli123 Group Title

here's what you do: sine of what angle will equal 5/13? Then you take that angle and take the tan of it.

13. rudra333 Group Title

but i how do i do that?

14. alanli123 Group Title

answer is 5/12 by the way

15. alanli123 Group Title

|dw:1358823550014:dw|

16. alanli123 Group Title

so... tan of theta is ?

17. rudra333 Group Title

how did u get 12? and one is negative

18. alanli123 Group Title

oops didn't catch the negative

19. alanli123 Group Title

so if its negative then it means the angle is either in the third or fourth quadrant

20. alanli123 Group Title

however my answer would still be correct if the angle was in the 3rd quadrant

21. rudra333 Group Title

@zaynahf

22. rudra333 Group Title

omg still confused

23. zaynahf Group Title

Im sorry, i dont know how to work this out.

24. rudra333 Group Title

k :(

25. alanli123 Group Title

did the problems include restrictions?

26. rudra333 Group Title

yes

27. alanli123 Group Title

what were they?

28. rudra333 Group Title

but that's all the questions says

29. alanli123 Group Title

?? so is there or is there no restrictions like 180<theta<270 (for exmaple)

30. alanli123 Group Title

@satellite73 help!!

31. rudra333 Group Title

no that is all the question says do u know the answer plz i am confused i will just do others if u don't know this

32. alanli123 Group Title

alright... shoot gimme another question

33. rudra333 Group Title

it is k i am doing graphing