CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    The angles of a triangle are in AP and the least angle is \[30{}^\circ \].The greatest angle in radians is:

    A)  \[\frac{7\pi }{12}\]                                         

    B)  \[\frac{2\pi }{3}\]

    C)  \[\frac{5\pi }{6}\]                           

    D)         \[\frac{\pi }{2}\]

    E)  \[\frac{\pi }{3}\]

    Correct Answer: D

    Solution :

    \[30{}^\circ =30{}^\circ \times \frac{\pi }{180}rad=\frac{\pi }{6}\] Let angle be \[a,\text{ }a+d,\text{ }a+2d\] Now,         \[3a+3d=\pi \] \[\Rightarrow \]\[3\frac{\pi }{6}+3d=\pi \]\[\Rightarrow \]\[d=\frac{1}{3}\left( \pi -\frac{\pi }{2} \right)=\frac{\pi }{6}\] \[\therefore \]Greatest angle\[=\frac{\pi }{6}+2.\frac{\pi }{6}=\frac{3\pi }{6}=\frac{\pi }{2}\]


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