CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2008

  • question_answer
    The perimeter of a certain sector of a circle is equal to the length of the arc of the semicircle. Then, the angle at the centre of the sector in radians is

    A)  \[\pi -2\]                            

    B)  \[\pi +2\]

    C)  \[\frac{\pi }{3}\]                             

    D)  \[\frac{2\pi }{3}\]

    Correct Answer: A

    Solution :

    Let the radius of circle be r. \[\therefore \] Length of an arc \[=\frac{\theta }{{{360}^{o}}}\times 2\pi r\] Since, perimeter of a sector of a circle = length of the arc of the semicircle                 \[\therefore \]  \[\frac{\theta }{{{360}^{o}}}\times 2\pi r+2r=\pi r\]                 \[\Rightarrow \]               \[\theta +2=\pi \]                 \[\Rightarrow \]               \[\theta =\pi -2\]


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