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Math Help - Need Help In These word problems

  1. #1
    Junior Member
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    Feb 2009
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    46

    Need Help In These word problems


    Let Me know if u have any problem reading it.

    Ok so for question 9 i got this
    a:0 show swimming distance is given by relationd d=wsecx
    cos x=w/d
    d=w/cosx
    d=wsecx

    B
    if l=2w determine the range of values that x may take on given that P can anywhere along the length of pool. so i tried these

    cosx=w/d will not work
    sinx=2w/d will not work
    tanx=2w/w
    tanx=2 inverse therefore
    0<x<1.07, is this right?

    C) im stuck in this question! please help any hints?
    D) I think i know how to do once i figured out c?
    E) same as D

    For question 10, im just confused any hints is appreciated
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  2. #2
    Newbie
    Joined
    Oct 2008
    Posts
    6

    Soln. to question 10 (a,b and d).

    (10a) line d // horizontal. Hence x = angle on the top right in the triangle, since alternate angles are equal.

    2/d =tanx
    2/tanx=d
    2cotx=d

    (10b)

    d=2/tanx
    d=2/tan(pi/3)
    d=1.15 metres

    (10d)

    Refer to the diagram in the question. When x approaches 0, then the window would get full sunlight (no shade). When x approaches pi/2, i.e. 90 degrees, then the window will get no sunlight (full shade). I hope this is correct.
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  3. #3
    Junior Member
    Joined
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    My answer

    Quote Originally Posted by jepal View Post

    Let Me know if u have any problem reading it.

    Ok so for question 9 i got this
    a:0 show swimming distance is given by relationd d=wsecx
    cos x=w/d
    d=w/cosx
    d=wsecx

    B
    if l=2w determine the range of values that x may take on given that P can anywhere along the length of pool. so i tried these

    cosx=w/d will not work
    sinx=2w/d will not work
    tanx=2w/w
    tanx=2 inverse therefore
    0<x<1.07, is this right?

    C) im stuck in this question! please help any hints?
    D) I think i know how to do once i figured out c?
    E) same as D

    For question 10, im just confused any hints is appreciated

    actually range of x you have selected is correct it is 0≤x≤ArcTan(2)
    values of d varies from w≤d≤√3 *w
    graph of d=w*sec(x) is some thing similar to this



    then the most interesting part of this problem comes
    take total distance along which the lifeguard has to swim is P
    then,
    P = LP + PS
    P = [ 2*w - w*tan(x) ] + w*sec(x)


    we can easily see if he runs along length and width he has to run about 3*w distance if he follows the diagonal length he has to swim only √3 *w

    you can observe it below ,



    you can see P decreases with x .
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  4. #4
    Junior Member
    Joined
    Feb 2009
    Posts
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    thank u!
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