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anonymous

  • one year ago

A ship leaves port A and travels for 60km in the direction 38 degrees. it then sails 40km in the direction 128 degrees to an island B . a) how far is B from A ? b)if the ship wishes to sail back directly to A from B , in what direction must it sail ?

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  1. welshfella
    • one year ago
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    |dw:1432990003731:dw|

  2. welshfella
    • one year ago
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    you need to find the length of AB

  3. welshfella
    • one year ago
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    to do this we need to find the value of angle ACB then we use the Cosine Rule to fin AB

  4. welshfella
    • one year ago
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    |dw:1432990207184:dw|

  5. welshfella
    • one year ago
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    angle ACB = 38+52 = 90 degrees so triangle ACB is right angled so we dont need the cosine rule Just use the pythagoras theorem AB^2 = 60^2 + 40^2

  6. welshfella
    • one year ago
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    can you find AB?

  7. welshfella
    • one year ago
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    just add 40^2 + 60^2 then take the square root

  8. welshfella
    • one year ago
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    use your calculator

  9. anonymous
    • one year ago
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    I GET 10

  10. welshfella
    • one year ago
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    ??? 60^2 = 3600 40^2 = 1600 adding 5200 so AB^ 2 = 5200 AB = sqrt 5200

  11. welshfella
    • one year ago
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    use your calculator to find the square root of 5200

  12. anonymous
    • one year ago
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    72.11

  13. welshfella
    • one year ago
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    yes so distance from A to B is 72 km

  14. welshfella
    • one year ago
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    * sorry 72.11

  15. anonymous
    • one year ago
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    and b) the direction ?

  16. welshfella
    • one year ago
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    b) the directions always start from the North line and are clockwise

  17. welshfella
    • one year ago
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    |dw:1432991016454:dw|

  18. welshfella
    • one year ago
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    Its the angle I've drawn around the point B

  19. anonymous
    • one year ago
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    so its 270 ?

  20. welshfella
    • one year ago
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    No its not 270 we need to find the value of angle CBA the angle next to it is 52 degrees then our direction will be 360 - 52 - <CBA

  21. anonymous
    • one year ago
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    this is confusing

  22. welshfella
    • one year ago
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    as triangle ABC is right-angled we casn use trigonometry tan CBA = 60/40 = 1.5

  23. welshfella
    • one year ago
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    |dw:1432991546898:dw|

  24. welshfella
    • one year ago
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    does that make it clearer?

  25. welshfella
    • one year ago
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    |dw:1432991638985:dw|

  26. welshfella
    • one year ago
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    that angle is 52 degrees as they are interior alternate angles

  27. welshfella
    • one year ago
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    tan CBA = 1.5 so you can find angle CBA

  28. welshfella
    • one year ago
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    then the direction = 360 - 52 - <CBA

  29. anonymous
    • one year ago
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    306.5

  30. welshfella
    • one year ago
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    what did you get for angle CBA?

  31. anonymous
    • one year ago
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    308 degrees

  32. welshfella
    • one year ago
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    ??? noo on your calculator enter tan-1 then 1.5 - or on some its the other way around

  33. anonymous
    • one year ago
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    56.31

  34. anonymous
    • one year ago
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    whats 108 for ?

  35. welshfella
    • one year ago
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    360 - 52 - 56.3

  36. welshfella
    • one year ago
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    forget the 108 - i got confused also!!

  37. anonymous
    • one year ago
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    yea

  38. anonymous
    • one year ago
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    nd whats 56.3 for ?

  39. welshfella
    • one year ago
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    thats the value of angle CBA

  40. anonymous
    • one year ago
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    BUH YEW SAID 360-52= ANGLE CBA WHICH IS 308

  41. welshfella
    • one year ago
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    so now you have what you require to find the direction it is 360 - 52 -56.3

  42. welshfella
    • one year ago
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    no i didnt say that

  43. anonymous
    • one year ago
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    OK NVM

  44. welshfella
    • one year ago
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    so what do you get for the direction?

  45. anonymous
    • one year ago
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    251.7

  46. welshfella
    • one year ago
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    yep thats it

  47. anonymous
    • one year ago
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    duh thanks

  48. welshfella
    • one year ago
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    yw

  49. anonymous
    • one year ago
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    |dw:1432992810256:dw| im send in the question .. pleas ehelp me with this last question

  50. anonymous
    • one year ago
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    a coast guard sees a boat B on the bearing of 30 degrees and a yatch Y on a bearing of 72 degrees . the bearing of the yatch from a boat is 136 degrees. a) calculate the values of D , E, F , the three angles of triangle CBY. b) what is the bearing of the coast guard from the yatch ?

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