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    Question

    The length of a side of an equilateral triangle is 18

    cm. The area (in cm²) of the region lying between the circumcircle and the incircle of the triangle is [use use π =22/7]
    A 252(4/7) Correct Answer Incorrect Answer
    B 254(2/7) Correct Answer Incorrect Answer
    C 254(4/7) Correct Answer Incorrect Answer
    D 248(2/7) Correct Answer Incorrect Answer

    Solution

    Side of the equilateral triangle = 18 cm Radius of circum - circle R = 18/√3 cm Radius of in - circle r = 18/2√3 = 9/√3 cm Area between the circum - circle and in – circle = π (R2 – r²)   = π (R+ r) (R-r) = (22/7) × (18/√3 + 9/√3) (18/√3-9/√3) = (22/7) × 27/√3 × 9/√3 = (81×22)/7 = 1782/7 cm² =254(4/7) cm2

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