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Math Help - Triangular prism

  1. #1
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    Triangular prism

    I believe or hope that i have solved the two cones with formula using
    S.A =PIr(s+r)
    =(3.14)(3)(6+3)
    =3.14(3)(9)
    =84.8yards

    I can't seem to be able to solve for the rectangular portion of the problem.

    Any help is greatly appreciated
    Last edited by mr fantastic; December 8th 2011 at 11:56 AM. Reason: Title.
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  2. #2
    Super Member Quacky's Avatar
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    Re: Having difficulties solving triangular prism

    To what question are you referring?
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  3. #3
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    Re: Having difficulties solving triangular prism

    My psychic powers are a little off today, would you please post a picture or description of the shape you are trying to evaluate the surface area of?
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  4. #4
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    Re: Having difficulties solving triangular prism

    Its not allowing me to transmit my attachment. I have no problems with it the other day
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  5. #5
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    Re: Having difficulties solving triangular prism

    MG_0003_math prism.jpg - Upload of file failed.

    i keep getting this message
    Attached Thumbnails Attached Thumbnails Triangular prism-img_0003_math-prism.jpg  
    Last edited by hotboxdriver; November 30th 2011 at 04:36 PM.
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  6. #6
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    Re: Having difficulties solving triangular prism

    The file was to large, so i needed to compress it.
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  7. #7
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    Re: Having difficulties solving triangular prism

    I only need to answer this question then i have completed lessons 1-10. In wishing to complete this course to return to college. I'm not asking for someone to do my work. I'm really asking is just for some direction, some ideas. Below is what i believe i have been able to solve so far. I'm not even sure if I'm using the right formula.

    S.A =PIr(s+r)
    =(3.14)(3)(6+3)
    =3.14(3)(9)
    =84.8yards
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  8. #8
    Super Member Quacky's Avatar
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    Re: Having difficulties solving triangular prism

    I'm slightly confused: how did you get that value for s? The way I see it, the radius of the half-cone is 3, but the height is 5, making s=\sqrt{34} by Pythagoras. Once you know this, you can calculate the surface area of the three rectangles and the surface area of the cone and put them together.
    Last edited by Quacky; December 7th 2011 at 06:54 PM.
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  9. #9
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    Re: Having difficulties solving triangular prism

    The sides was just an estimated guess of 6. I don't know how to figure the value for the sides. So, the sides would actually be 5.8 ?
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  10. #10
    Super Member Quacky's Avatar
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    Re: Having difficulties solving triangular prism

    Quote Originally Posted by hotboxdriver View Post
    The sides was just an estimated guess of 6. I don't know how to figure the value for the sides. So, the sides would actually be 5.8 ?
    No, they would be \sqrt{34}. Try to keep things in an exact form until the final stages of your working. Do you understand how I got to that conclusion?
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  11. #11
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    Re: Having difficulties solving triangular prism

    yes,
    solving for the sides using Hypotenuse rule X2=5^2+3^2=25+9
    =√34
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