Question

    In a regular polygon, the ratio of the exterior angle to

    the interior angle is 4:5. Find the interior angle of the polygon.
    A 140° Correct Answer Incorrect Answer
    B 80° Correct Answer Incorrect Answer
    C 100° Correct Answer Incorrect Answer
    D 120° Correct Answer Incorrect Answer

    Solution

    Sum of an exterior angle and interior angle of a regular polygon = 180 o  (Linear pair)

    Let the exterior angle and the interior angle of the given polygon be 4x and 5x, respectively

    4x + 5x = 180°

    Or, 9x = 180°

    Or, ‘x’ = (180°/9) = 20°
    Required angle = 5x = 100°

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