Quantcast

A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

kaylala

  • one year ago

TOPIC: Trigonometry GIVEN THE FOLLOWING CONDITIONS: sin A = 4/5, A Σ I sin B = -3/5, B Σ III Find the value of: I. sin (A +- B) II. cos (A +- B) III. tan (A +- B)

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

    @Callisto

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

    @eliassaab

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

    I do not understand what comes after 4/5 and -3/5

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

    let me fix the question

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

    Also look at this summary of trig formulas, your problem follows easily http://www.math.missouri.edu/escgi/mucgi-bin/trigidentities.cgi

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

    It is still not fixed

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

    it is. see this pic that i will post. it's where i got the question. wait

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

    You need these formulae sin(a + b ) = sin(a) cos(b) + sin(b) cos(a) sin(a - b ) = sin(a) cos(b) - sin(b) cos(a) cos(a + b ) = cos(a) cos(b) - sin(a) sin(b) cos(a - b ) = cos(a) cos(b) + sin(a) sin(b)

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

    oh it's (+_) the plus on top of the minus for I - III

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

    You do first + than -

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

    You need six answers

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

    Where is the picture?

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

    wait. i just took a picture of it

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

    1 Attachment
  15. Yttrium
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    @eliassaab , I think the information beside 4/5 and -3/5 are the position of angle in the cartesian plane. (specifically Quadrant I for <A and Quadrant III for <B

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

    @eliassaab here's the picture

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

    and yes those are values for the carthesian plane @Yttrium

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

    i dont think i have to find 6 answers @eliassaab

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

    somebody. anyone. please help

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

    You really have to find 6 ansers @kaylala. Let me tell you this: \[\sin (A \pm B)\] is the notation for\[\sin (A+B)\] and \[\sin(A-B)\] I hope you understand now.

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

    oh okay i see now @Yttrium

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

    i just dont know how to start this

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

    let's start with angle A

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

    the condition says sinA = 4/5, where it is in quadrant 1. we know that sinx = opp/hyp Hence, the figure much look like this. |dw:1391508636187:dw|

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

    okay

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

    |dw:1391508787128:dw| let's say that adjacent side of A is x. Can you solve x now?

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

    okay x=sqrt-9 ??? @Yttrium

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

    isn't is sqrt(+9)? which is 3?

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

    oh my bad

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

    it do is 3

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

    Yea it is. And, with that you can now actually solve for cosA, tanA.

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

    how?

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

    i really dont know how to do this please guide me @Yttrium

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

    cosA = adj/hyp tanA = opp/adj did you forget that?

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

    sorta

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

    cos A = 3/5 ???

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

    tanA=4/3

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

    did i get it?

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

    what do i do next?

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

    You got this. I think it is better if you write sinA, cosA, and tanA in a piece of paper. They are really important later. Next thing we are going to do is to solve for cosB and tanB

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

    yeah. just wrote it down already how do i solve for that?

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

    y=4

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

    ? @Yttrium

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

    you sure? isn't it -4? take note it is in the quadrant III.

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

    okay so the quadrant determines the sign? right?

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

    Yeah. for (x,y) quadrant I (+,+) II (-,+) III (-,-) IV (+,-) Now. Find cosB and tanB. Be careful with the signs.

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

    okay then

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

    Solve for cosB and tanB

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

    cos B= -4/5

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

    tanB= 3/-4

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

    Ohhh wait!!!

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

    did i get it?

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

    ookay

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

    the graph will be like this |dw:1391510194742:dw|

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

    x then is -4 solve again for cosB and tanB

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

    i see now but the answer for cos b and tan B still remains?

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

    so are those the answers already?

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

    what to do next?

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

    @Yttrium

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

    ooops tanB = -3/-4 = 3/4

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

    oh you're right

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

    Now is the time to evaluate them. I. sin (A +- B) = sinAcosB +- cosAsinB II. cos (A +- B) = cosAcos -+ sinAsinB

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

    III. \[\tan(A \pm B) = \frac{ tanA \pm tanB }{ 1\mp tanAtanB }\]

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

    how's that? do i just substitute what i got? to the given formulas?

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

    Yeah. All the operation found upside are the only operations used when applying upside identities. Look at this. \[\tan(A +B) = \frac{ tanA + tanB }{ 1 - tanAtanB }\]

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

    so sin(a+b) = 1 sin(a-b) = -7/25 ??? @Yttrium

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

    cos (a+b)=0 cos (a-b)=-24/25 did i get it correctly @Yttrium ?

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

    i'll just check the sin function, you take care of the others :D sin(a+b) = -1

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

    okay :) thanks

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

    tan (A+B)= undefined??? is it? please check this @Yttrium

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

    what is tanA and tanbB?

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

    tanA=4/3 tanB=3/4

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

    Yeah. That's undefined. And that is normal. :))

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

    i see. okay thanks again :)

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

    No problem :))

  76. 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.