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anonymous

  • one year ago

Hi, i ask this the other day and if someone can solve it with answer and explains, will fan and medal: When a beam makes an angle of 40 degrees with the ground, the top of the beam is 40 feet above the ground. There a telephone wires near by and the worker worried that the beam may hit the wires. When the beam makes a angle of 60 degrees with the ground, the wires are 2 feet above the beam. Will the beam hit the ground if the crew continues to raise it?

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  1. anonymous
    • one year ago
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    @Nnesha

  2. Nnesha
    • one year ago
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    looks like physics q lel :P well i have to go wait for someone or i'll llook at 't later !

  3. anonymous
    • one year ago
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    okay :)

  4. radar
    • one year ago
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    |dw:1439431270274:dw| I believe the question should be does the pole hit the WIRE as they continue to raise it, it will hit the ground if they drop it.!

  5. anonymous
    • one year ago
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    @radar: i'm sorry, it suppose to be if it hit the wires or not.

  6. mathstudent55
    • one year ago
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    |dw:1439437785859:dw|

  7. mathstudent55
    • one year ago
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    Let's look at the beam at 40 deg to the ground.

  8. mathstudent55
    • one year ago
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    |dw:1439437990141:dw|

  9. mathstudent55
    • one year ago
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    \(\sin 40^o = \dfrac{40~ft}{L}\) \(L = \dfrac{40~ft}{\sin 40^o} \approx 62.23 ~ ft\)

  10. mathstudent55
    • one year ago
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    Now we know the length of the beam. Now we look at the situation when the beam is at 60 degrees from the ground.

  11. mathstudent55
    • one year ago
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    |dw:1439438459934:dw|

  12. mathstudent55
    • one year ago
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    Notice I just corrected the length of the beam. I just noticed my calculator was set to radians and the length of the beam was incorrect. The length of the beam is 62.23 ft. This number is correct now.

  13. mathstudent55
    • one year ago
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    Now we find h, the height of the beam when it is at a 60-deg angle with the ground.

  14. mathstudent55
    • one year ago
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    \(\sin 60^o = \dfrac{h}{62.23~ft} \) \(h = (62.23~ft)\sin 60^o \approx 53.89~ft \)

  15. mathstudent55
    • one year ago
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    Since the wires are 2 ft higher than the top of the beam when the beam is at 60 deg with the ground, the wires are at 55.89 ft above the ground.

  16. mathstudent55
    • one year ago
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    Since the beam is 62.23 ft long, and the wires are only 55.89 ft above ground, if the crew continues to raise the angle of the beam, the beam WILL HIT the wires.

  17. mathstudent55
    • one year ago
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    At what angle of the beam will it hit the wires? |dw:1439438842464:dw|

  18. anonymous
    • one year ago
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    Beware the OS Code of Conduct!

  19. mathstudent55
    • one year ago
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    \(\sin x = \dfrac{55.89}{62.23} \) \(\sin^{-1} \dfrac{55.89}{62.23} = 63.91^o\) At 63.91 deg, the beam will hit the wires.

  20. mathstudent55
    • one year ago
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    @Leong Do you understand?

  21. anonymous
    • one year ago
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    @mathstudent55 yes :) thank you :) I was just drawing it again and again but didn't think of the law of sines :)

  22. mathstudent55
    • one year ago
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    I did not use the law of sines. This is simply the definition of the sine in a right triangle.

  23. mathstudent55
    • one year ago
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    |dw:1439439303636:dw|

  24. mathstudent55
    • one year ago
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    We used the sine ratio which is opp/hyp. |dw:1439439409054:dw|

  25. mathstudent55
    • one year ago
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    To find the length of the beam, we did this: |dw:1439439471920:dw|

  26. mathstudent55
    • one year ago
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    To find the heigth the beam reaches at 60 deg, we did this: |dw:1439439571183:dw|

  27. anonymous
    • one year ago
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    wait, so like the beam will hit the wires at 60 something degree, because Sin^-1(53.89 over62.23 =59.99

  28. mathstudent55
    • one year ago
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    It equals 63.91 deg. Yes, when the beam is at 63.91 deg with the ground, the beam will hit the wires.

  29. anonymous
    • one year ago
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    okay, thanks. i bad at round numbers

  30. mathstudent55
    • one year ago
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    No problem. You're welcome.

  31. Nnesha
    • one year ago
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    cool ,-,

  32. radar
    • one year ago
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    You beat me to this, @mathstudent55 and did an excellent step by step job. I could not done any better or clear explanation. You certainly deserve the medal.

  33. mathstudent55
    • one year ago
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    @radar A good word from you means a lot to me. I really appreciate it. Also, thanks for the testimonial.

  34. anonymous
    • one year ago
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    @mathstudent55 hey, so I got a mistake that the when th beam make angle of 40 degree then from the beam to the ground is 8ft, so the beam won't hit the wires since we know that the beam is 12,45 ( I had calculator again myself) and when it make angle of 60 then from the beam to the sruface is 10,78. by that, the beam WILL NOT hit the wires, so do I have to find anything else when I know that the beam will not hit the wires?

  35. radar
    • one year ago
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    Please post the problem again, providing correct info. The problem as presently posted, states that at 40 degrees elevation, the top of the beam is 40 ft. above the ground. How you got 12.45 ft. is not clear.

  36. anonymous
    • one year ago
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    okay

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