Smile 發問於 科學及數學數學 · 1 月前

Maths problem:為何答案是C?

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  • 匿名
    1 月前
    最愛解答

    Question:

    The figure shows 4 identical circles. If the perimeter of the shaded region is 2π cm, find the area of the shaded region.

    A. 4(π - 1) cm³  B. (4 - π) cm³  C. 2(π - 1) cm³  D. (π - 2) cm³

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    Solution:

    Let r be the radius of a identical circle.

    In the picture 1,

    A perimeter of an identical circle = the perimeter of the shaded region

    2πr = 2π

    r = 1

    In the picture 2,

    The area of the shaded region

    = Area of the square - ( Area of an identical circle )

    = (1 + 1)² - 1²π

    = 4 - π

    ∴ B. (4 - π)

    Attachment image
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