Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

AonZ Group Title

Pls Pls Pls help... I have been stuck for a while!!! Prove tan3x = (3tanx - tan^3 x) / ( 1 - 3tan^2 x) using sin3x/ cos3x = tan3x sin3x = 3sinx - 4sin^3 x cos3x = 4cos^3 x - 3cosx

  • one year ago
  • one year ago

  • This Question is Closed
  1. .Sam. Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Have you tried using\[\tan(3x)=\tan(2x+x)\] Then \[\tan(A+B)=\frac{tanA+tanB}{1-tanAtanB}\]

    • one year ago
  2. AonZ Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    the question asked to solve it using tan3x = sin3x / cos3x :/

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

    |dw:1369139564173:dw|

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

    can you pls post it :) May help me solve it :)

    • one year ago
  5. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    factor out sin and cos

    • one year ago
  6. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    (3sinx - 4sin^3 x)/(4cos^3 x - 3cosx) (sinx)(3-4sin^2(x))/((cosx)(4cos^2(x)-3)

    • one year ago
  7. AonZ Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    my way was to factor out sin and cos so it was tanx times something then i divided the numerators by cos^2 x then im stuck

    • one year ago
  8. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Pick a trig function, sine or cosine

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

    any :)

    • one year ago
  10. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Thanks, loser66

    • one year ago
  11. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    so, let's go with sine cos^2(x)=1-sin^2(x), right?

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

    yep

    • one year ago
  13. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    plug in (1-sin^2(x)) for cos^2(x) (sinx)(3-4sin^2(x))/((cosx)(4cos^2(x)-3)

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

    yea i actually tried that :P

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

    after doing that would you divide by cos^2 x?

    • one year ago
  16. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    wait up look at the tan(3x) expression can't you clean that up a bit?

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

    possibly... But you could always change it both ways

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

    this is the last step i got to|dw:1369140948450:dw|

    • one year ago
  19. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    1/cos^2(x) is sec^2(x), right?

    • one year ago
  20. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    use the tangent-secant identity

    • one year ago
  21. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    1+tan^2(x) = sec^2(x)

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

    !!!! :D ur awsome

    • one year ago
  23. trumpetmaster7777 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Thank you :D

    • one year ago
  24. AonZ Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    on denominator its still sec^2 - 4tan^2 ... errr im lost again

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

    Would that help? sec^2 = 1 + tan^2

    • one year ago
  26. AonZ Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    oh yes :)

    • one year ago
    • Attachments:

See more questions >>>

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.