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Math Help - Surface area of a triangular prism...

  1. #1
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    Surface area of a triangular prism...

    Hello everyone. I'm hoping someone can give me a little bit of help. Here's the deal, I helped a friend with her homework - calculating the surface area of triangular prisms - a couple of nights ago. It looks like I've done something wrong, however, because when she returned home she hadn't gotten a single correct answer. Anyway, here's what I've got, maybe someone can tell me if my answers are correct. This is the formula that I used: ab+ (s1+s1+s3)h

    1: 144 square inches
    6x8 + (10 + 6 + 8)4 = 144

    2: 216 square feet

    3: 48 square km

    4: 60 square cm

    5: 212 square yards

    6: 84 square inches


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  2. #2
    Super Member

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    Lexington, MA (USA)
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    Hello, Sherpa!

    Your formula is correct.
    . . Your answers should have been correct.


    Code:
            *
           /    *
          *         *
          |   *         *
          |       *         *
        a |         c *         *
          |               *         *
          |                   *    / h
          * - - - - - - - - - - - *
                      b

    The triangular faces are all right triangles.

    . . The area of a triangle is: . \tfrac{1}{2}ab\text{ units}^2

    . . Hence, the area of two triangles is: . ab\text{ units}^2


    There are three rectangluar panels.
    . . Their areas are: . ah,\;bh,\;ch\text{ units}^2


    Therefore, the total surace area is: . S \;=\; ab + (a+b+c)h

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  3. #3
    Newbie
    Joined
    Feb 2010
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    It looks like the teacher has his formulas wrong! I guess I should explain that to him.
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