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    If the interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11, then the measure of the smallest interior angle is:
    Question

    If the interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11, then the measure of the smallest interior angle is:

    A.

    10°

    B.

    20°

    C.

    25°

    D.

    15°

    Correct option is B

    Given:

    The interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11.

    Concept Used:

    The sum of the interior angles of a polygon with n sides is given by the formula (n - 2) ×\times​ 180°.

    A pentagon has 5 sides.

    Solution:

    Calculate the sum of the interior angles of a pentagon:(5 - 2) ×\times​180° = 3 ×\times 180° = 540°​

    Let the angles be x, 3x, 5x, 7x, and 11x.

    x + 3x + 5x + 7x + 11x = 540°

    27x = 540°

    x =540°27 \frac{540° }{ 27}​​

    x = 20°

    The smallest interior angle is x, which is 20°.

    Therefore, the measure of the smallest interior angle is 20°.

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