Question

    Find the length of the side of a regular octagon which

    is formed by cutting the corner of square of side 20 cm?
    A 20(√2+1) Correct Answer Incorrect Answer
    B 20(√2-1) Correct Answer Incorrect Answer
    C 10(√2+1) Correct Answer Incorrect Answer
    D 10(√2-1) Correct Answer Incorrect Answer

    Solution

    Let the sides of regular octagon be a. a² = x² + x² a² = 2x² x² = a²/2 x = a/√2 x + a/√2 + a = 20 a/√2 + a/√2 + a = 20 a(√2+1) = 20 ∴ a = 20/(√2+1) ⇒ a = 20(√2-1)

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