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德駿 發問於 科學及數學數學 · 1 十年前

ratio of area

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In the figure,AC:EC=5:4 and AD:DB=1:2.Find the ratio of the area of△CDE to that of △BCD

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2 個解答

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  • 1 十年前
    最愛解答

    AC:EC=5:4

    AE:EC=1:4

    let x be area of △ADE

    area of △CDE = 4x (高一樣,底比數 1:4, 三角形面積 = (1/2)高*底)

    so, area of △ACD = 5x

    area of △BCD = 10x (高一樣,底比數 1:2)

    area of △CDE : area of △BCD = 4x : 10x = 2 : 5

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  • 1 十年前

    Note that if the height is the same, ratio of area = ratio of base length

    Area △BCD : Area △ACD = 2 : 1 = 10 : 5

    Area △ACD : Area △CDE = 5 : 4

    Therefore

    Area △BCD : Area △CDE = 10 : 4 = 5: 2

    2007-06-17 20:12:57 補充:

    唔明邊道呀 ?

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