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berrypicking

  • 3 years ago

solve equation in the interval from 0 to 2pi. 7 cos 2t =3

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  1. berrypicking
    • 3 years ago
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    corrections 7 cos 2t=3

  2. cwrw238
    • 3 years ago
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    arccos 3/7 - your calculator will give u the value of t in first quadrant the other value is in 4th quadrant

  3. berrypicking
    • 3 years ago
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    what does arccos mean

  4. berrypicking
    • 3 years ago
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    am I setting calculator in rad. or degrees

  5. cwrw238
    • 3 years ago
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    oh - then find angle whose cos is 3/7 0 calculator will give you value of 2t in first quadrant

  6. cwrw238
    • 3 years ago
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    right - set to rad arccos means the angle whose cos is given value or - on calculator button this might be cos -1

  7. berrypicking
    • 3 years ago
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    cos 3/7= .91 now what

  8. berrypicking
    • 3 years ago
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    how do I get the other value

  9. cwrw238
    • 3 years ago
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    you need cos-1 not cos check again : i make it 1.128 rad

  10. berrypicking
    • 3 years ago
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    ok that is 1.099??

  11. berrypicking
    • 3 years ago
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    1/cos(3/7) right?

  12. berrypicking
    • 3 years ago
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    and how do you know I need cos-1 and not cos?

  13. cwrw238
    • 3 years ago
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    no - the cosine of the angle 2t = 3/7 you need to find the angle whose cosine is 3/7 first find 3 / 7 on ur calculator then you need to press the cos-1 (or arccos) button

  14. berrypicking
    • 3 years ago
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    do I just press cos then -1

  15. cwrw238
    • 3 years ago
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    cos-1 does not mean 1 / cos in this context

  16. cwrw238
    • 3 years ago
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    no there is probably a button marked cos but you first press the shift key then cos button to get value of the angle

  17. cwrw238
    • 3 years ago
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    cos-1 notation is a bit confusing - in Europe they use arccos which makes more sense

  18. berrypicking
    • 3 years ago
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    cos (3/7)=.91. Do I press shift key before entering cos (3/7)? don't know the shift key

  19. berrypicking
    • 3 years ago
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    I haven't done any problems with cos-1

  20. cwrw238
    • 3 years ago
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    calculators vary you either press shift cos (3/7) or (3/7) shift cos

  21. cwrw238
    • 3 years ago
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    the correct value is 1.127 (to 3 dec places)

  22. cwrw238
    • 3 years ago
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    sorry 1.128

  23. cwrw238
    • 3 years ago
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    its a bit hard to explain without seeing your calculator....

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