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Math Help - Similar solids

  1. #1
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    Similar solids

    Hi I really need help with the following question. Please help me!
    Attached Thumbnails Attached Thumbnails Similar solids-q2.jpg  
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  2. #2
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    Re: Similar solids

    Strange.......

    the ratio of the two volumes is equal to the qubic power of the ratio of the two heights
    therefore find the ratio of the two volumes ..get the qubic root and then use this ratio to find the height of the two pyramides...it is easy.

    The same applies for the total surface but here the ratio between the two surfaces is equal to the square of the ratio of the two heights.
    You need however the slant height of one triangle to calculate the area of one triangle. ..........
    Last edited by MINOANMAN; June 19th 2013 at 12:21 AM.
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  3. #3
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    Re: Similar solids

    512/64= 2^9/2^6= 2^3= 8. All lengths in the larger pyramid are \sqrt[3]{8}= 2 times the corresponding length in the smaller pyramid. All areas in the larger pyramid are 2^2= 4 times the corresponding area in the larger pyramid.

    Since the height of the larger pyramid is 36 cm. the height of the smaller pyramid is 36/9= 4.5 cm. Now find the distance between the bases.

    Since the problem only asks for the ratios of the areas, there is no need to calculate the actual areas themselves and so no need for the slant height.
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