A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Find the exact value of cos^(-1)(cos(17pi/5))?

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

    Can you put that in equation form using the equation button located on the left of the "Post" button?

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

    \[\cos^{-1}(\cos( 17\pi/5))\]

  3. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Aye!

  4. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Now that's better!

  5. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Based on my calculations, \[\frac{ 3\pi }{ 5 }\]

  6. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    @_alex_urena_ what's the \(cos(\pi)?\)

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

    what do you mean @jdoe0001 ?

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

    how did you get that @chrisdbest ?

  9. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ohh, just that... if you were to get the \(cos(\pi)\) what would that give you?

  10. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Sure, I'll tell you

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

    -1? @jdoe0001

  12. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok... so... what is now the \(cos^{-1}(-1)?\)

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

    pi

  14. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yeap.... thus... one sec

  15. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \(\bf cos(\pi )={\color{brown}{ -1}}\qquad cos^{-1}({\color{brown}{ -1}})=\pi \\ \quad \\ \textit{thus we could say that }cos^{-1}[cos(\pi )]=\pi \\ \quad \\ \textit{thus, we could also say that }cos^{-1}\left[ cos\left( \cfrac{17\pi }{5} \right) \right]\implies \cfrac{17\pi }{5}\)

  16. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    What he's trying to say is that when you have an inverse cosine and a cosine, they cancel out

  17. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so in short, \(\bf cos^{-1}[cos(whatever)]=whatever\qquad \\ \quad \\sin^{-1}[sin(whatever)]=whatever \\ \quad \\ tan^{-1}[tan(whatever)]=whatever\)

  18. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Lols, that's basically what I said

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

    so the answer is 17pi/5 ?

  20. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    It might, I thought it was 3pi/5

  21. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yeap, unless, the inverse function apply, which so far I don't see they do

  22. jdoe0001
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    inverse functions restrictions I meant, doesn't seem like in this context they do

  23. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Because the way you wrote it in equation form, I plugged that into my calculator the same way, and I got 3pi/5

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

    hmmm well how did you get 3pi/5 @chrisdbest

  25. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Because the way you wrote it in equation form, I plugged that into my calculator the same way, and I got 3pi/5

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

    ok but how would you do without the calculator? or do you have to use one to solve this problem?

  27. chrisdbest
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I use one to solve the problem.

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

    hmmm ok thnx

  29. 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.