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    Question

    Length of a chord in a circle of radius 'r' cm, is 16 cm

    and distance between chord and centre of the circle is 15 cm. Find the value of (5r - 19).
    A 62 Correct Answer Incorrect Answer
    B 66 Correct Answer Incorrect Answer
    C 70 Correct Answer Incorrect Answer
    D 74 Correct Answer Incorrect Answer

    Solution


    Image
    AB is the chord of circle.
    Perpendicular line joining the centre of circle and chord, bisects the chord.
    i.e. AC = BC = (16/2) = 8 cm
    By Pythagoras theorem,
    OA 2 = OC 2 + AC 2
    Or, r 2 = 15 2 + 8 2
    Or, r 2 = 225 + 64
    Or, r 2 = 289
    So, 'r' = 17
    But length cannot be negative. So, 'r' = 17
    Required value = 5 X 17 - 19 = 66

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