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    Question

    What is the area of a circle whose radius is equal to the

    length of a cube’s edge, if the cube's total surface area is 1,944 cm²? (Take π = 3)
    A 772 cm² Correct Answer Incorrect Answer
    B 972 cm² Correct Answer Incorrect Answer
    C 922 cm² Correct Answer Incorrect Answer
    D 572 cm² Correct Answer Incorrect Answer

    Solution

    ATQ,

    Total surface area of cube = 6 × edge²

    So, 6 × edge² = 1,944

    Or, edge² = 324

    Or, edge = ±18

    But edge cannot be negative.

    So, edge = 18 cm

    Area of circle = π × radius² = 3 × 18² = 3 × 324 = 972 cm²

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