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anonymous

  • one year ago

Given sin (theta) = 21/29... find sin cos and tan (2 theta)

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  1. Loser66
    • one year ago
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    \(sin(\theta)=\dfrac{opposite}{hypotenuse}\) how about cos(theta)?

  2. anonymous
    • one year ago
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    adj / hyp

  3. Loser66
    • one year ago
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    ok, let them there. Now, pythagorean |dw:1435110885323:dw| Can you put numbers on the triangle?

  4. Loser66
    • one year ago
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    on that triangle, which side is hypotenuse?

  5. anonymous
    • one year ago
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    left side is hyp bottom is adj and right side is opp

  6. Loser66
    • one year ago
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    you use draw box below, click on it, then a box will pop up. On the right corner, you will see "copy previous drawing", click on it, then scroll up to see my picture, click it to get the pic, then put the numbers in, then post

  7. Loser66
    • one year ago
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    |dw:1435111234190:dw|

  8. Loser66
    • one year ago
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    hence, the adj side can be calculated by Pythagorean. Do you know him?

  9. Loser66
    • one year ago
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    don't get??

  10. anonymous
    • one year ago
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    oh a2 + b2 = c2

  11. Loser66
    • one year ago
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    Mr. Pythagore said : In this case, \(adj = \sqrt{29^2-21^2}=??\)

  12. Loser66
    • one year ago
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    knock knock!!! adj =??

  13. Loser66
    • one year ago
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    Don't get or you got the answer?? If you don't answer me, I am out in 2 more minutes.

  14. anonymous
    • one year ago
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    gimme one second

  15. anonymous
    • one year ago
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    35.8?

  16. Loser66
    • one year ago
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    redo.

  17. anonymous
    • one year ago
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    wait why is it minus?

  18. anonymous
    • one year ago
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    isnt the formula a squared plus b squared equals c squared?

  19. Loser66
    • one year ago
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    a^2 +b^2 =c^2, hence a^2 = c^2 -b^2

  20. anonymous
    • one year ago
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    ahhhh got it

  21. anonymous
    • one year ago
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    so its asking for 2 theta not just theta

  22. anonymous
    • one year ago
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    i got that the adj is 20

  23. Loser66
    • one year ago
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    yup

  24. Loser66
    • one year ago
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    now, you have all of them, plug in cos (theta) = adj/ hyp = ???

  25. anonymous
    • one year ago
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    no i get that part but i need to find sin (2 theta) cos (2 thetha) and tan 2 (theta)

  26. anonymous
    • one year ago
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    cos(theta) = 20/29

  27. Loser66
    • one year ago
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    ok, tell me cos (theta) =??

  28. anonymous
    • one year ago
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    20/29

  29. Loser66
    • one year ago
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    yup

  30. anonymous
    • one year ago
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    now how do i find 2 theta?

  31. Loser66
    • one year ago
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    now \(sin(2\theta) = 2 sin(\theta)cos(\theta)\)

  32. Loser66
    • one year ago
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    just plug numbers in, right?

  33. anonymous
    • one year ago
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    ahh gotcha so cos (theta) = 2cos (0) tan (0)?

  34. Loser66
    • one year ago
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    nnnnnnnnnnnnnnnnnoppppppppppe

  35. Loser66
    • one year ago
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    \(cos(2\theta)= cos^2(\theta)-sin^2(\theta)\)

  36. anonymous
    • one year ago
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    what is this called? i feel like i should google these formulas lol

  37. Loser66
    • one year ago
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    just type double angle trig formula.

  38. Loser66
    • one year ago
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    But, you should memorize some easy formulas.

  39. anonymous
    • one year ago
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    got it thank you so much

  40. Loser66
    • one year ago
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    ok, and you know tan = sin /cos, right?

  41. anonymous
    • one year ago
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    its not 2 tan ( ) / 1 - tan ^2 ( )?

  42. Loser66
    • one year ago
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    you have sin (2 theta), cos (2 theta), why don't you use them?

  43. Loser66
    • one year ago
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    \(tan (\color{red}{x}) =\dfrac{sin(\color{red}{x})}{cos(\color{red}{x})}\) \(tan(\color{blue}{2x})=\dfrac{sin(\color{blue}{2x})}{cos(\color{blue}{2x})}\) got it?

  44. anonymous
    • one year ago
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    oh okay makes sense

  45. Loser66
    • one year ago
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    good luck. I am out now

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