A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Find an exact value. sine of negative eleven pi divided by twelve.

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella

  2. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sien -11 p / 12 now we can find the value of sine of -11pi/ 6 which is half of -11pi/12

  3. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1438258865764:dw|

  4. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    - sin 11pi/6 = sin pi/6 = 1/2

  5. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sin(11pi+pi/6)=1/2 so, sin(-11/12)=....

  6. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    now to find sin -11pi/12 we using the half angle formula sin -11pi/12 = sin pi/6 ------------ 1 + cos pi/6

  7. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i'll just check that is ok - - im relying on my memory here

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait I'm still a little lost

  9. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oops sorry thats the half-angle tan formula

  10. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i mad a mistake there where are you lost?

  11. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    well I wouldn't say lost, I was here for this lecture and I don't know where these numbers are coming from.

  12. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wasn't

  13. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    hey.... sin(pi/12-pi) =sin pi/12*cos pi - sin pi * cos pi/2 =.25882(-1) -0 =-.25882

  14. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    using Trignometry identity.... sin(a-b)=sinacosb - cosasinb

  15. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    This should help....

  16. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    and above you are wondering how did .25882 come, its the value of sin(pi/12)

  17. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok, ya I'll get back to it later I have class soon. Thanks guys! :)

  18. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    now how did I bring sin(pi/12) value....

  19. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay... will wait.....

  20. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Really I have to go but I'll be back on in 2-3 hours.

  21. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    That cool? :)

  22. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @arindameducationusc - you have a correct answer using the calculator but she wants an exact answer derived form known values like pi/6 = 1/2 and a trig identity. I got the wrong identity.

  23. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok.

  24. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Remember your formulas. \(\sin(\alpha + \beta) = \sin(\alpha)\cdot \cos(\beta) + \cos(\alpha)\cdot \sin(\beta)\)

  25. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok.

  26. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So let's say... \(-\dfrac{11\pi}{12} = -\dfrac{2\pi}{3}-\dfrac{\pi}{4}\) Can you go from there?

  27. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    It's all a little plug and chug from there.

  28. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes thats a good way to do it

  29. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    another way would be to use the identity sin^2 (-11p/12) = [ 1 - cos (-11pi/6) ]/ 2

  30. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh that's another way, didn't think of that one too quickly.

  31. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    You have a good day @welshfella , See ya around :)

  32. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea theres so many trig identities - I used to know them all when i was younger Memories a bit hazy now!!1

  33. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea you too

  34. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella sin15 can be derived easily....

  35. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Sin(45-30)... Using identity @welshfella I would have written it but she went offline

  36. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes

  37. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thats another way too

  38. arindameducationusc
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella Thumbs up :)

  39. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    u should close this now lol @clairvoyant1

  40. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.