A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • 5 years ago

Help with trigonometry identities please! Simplify: a) cos(180º +x) + cos(180º - x) b) cos(7pi/126º)cos(36º/5)+sin(7pi/126º)sin(36º/5)

  • This Question is Closed
  1. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cos(a+b) - cos(a-b): cos^2(a) - sin^2(a) + cos^2(a) + sin^2(a) 2cos^2(a) 2cos^2(180) ; cos(180) = -1 2(-1^2) = 2(1) = 2

  2. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[7\pi/126^O\] ????

  3. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if anything that would equal 7pi(180)/126pi ... but ive never seen anything written like that before.

  4. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    this is the equation:

    1 Attachment
  5. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    well, its a cos(a-b) construct, but i dunno about those digits

  6. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if you convert the degrees to radians, then I spoose you can have a radian measure without a pi in it.... but its just unnatural :)

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

    ok..thanks for the help on the first one

  8. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    7pi = 180 degrees, lets substitute that in instead

  9. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cos(180/126)cos(36/5) + sin(180/126º)sin(36/5)

  10. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    then cos(180/126 - 36/5) is your angle....

  11. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    add the fractions and simplify... right?

  12. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    3636 ----- 630

  13. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    602/105...whats our remainder?

  14. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did u already multiply the fraction by cos? im confused, sorry :S

  15. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    5 + (77/105)

  16. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you dont need to do that :) you just need to find the angle of the cos: cos(a - b); find a - b

  17. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    108(5) 36(126) ------ - -------- 126(5) 126(5)

  18. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    180(5) 36(126) ------ - -------- 126(5) 126(5) arghh!!..typoed it lol

  19. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    3636 cos of ----- is what I get 630

  20. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    -3636 ------ you gotta catch this stuff, cause I dont always ;) 630

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

    Amistre please help :'(

  22. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that looked alot better in my head lol

  23. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    loco..... give me a sec; im on break ;)

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

    ok

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

    im not about to catch anything lol. i am very confused by trig in general..im about to post a question on trig identities...could u maybe help me through those when i post it? u seem like u know what ur doing :)

  26. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    its a farse, I no nutheeenng!!!

  27. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    he does. he know his stuff :)

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

    ur a superhero for a reason :)

  29. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    pfftt!!!.....super hero, now I gotta wear tights, and that aint a pretty picture ;)

  30. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I get an angle of -5.77 degrees when we do all that.

  31. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that is if its even right lol

  32. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the cos of that angle = .9949 and thats the best I got fer ya on that one....right or wrong ;)

  33. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    r u solving the whole question btw? i just need to simplify..

  34. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I solved it for the angle; andle = 5 + (77/105) and for the value of the cosine of that angle :=: .9949 how to simplify it is beyond me :)

  35. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    :'( ok. that's better than no answer at least!

  36. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    well, -5 and 77/105ths.... but yeah :) ..good luck with it; if anything, get it wrong and move ahead :)

  37. 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.