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匿名 發問於 科學及數學數學 · 6 年前

Geometry question 7

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1 個解答

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  • 6 年前
    最愛解答

    Denote the mid-point of AB as O, then O is the centre of the cicle.

    OA = OB = OE = 6

    so AD = OE = 6

    The area of rectangle ABCD = 12 × 6 = 72

    The area of triangle ACD = 72/2 = 36

    The area of the white part at the top left

    = 6² - (1/4) π 6²

    = 36 - 9π

    Therefore, the area of the shaded region

    = 36 - (36 - 9π)

    = 9π

    (A)

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