JEE Main & Advanced Mathematics Trigonometric Equations Question Bank Circle connected with triangle

  • question_answer
    If the radius of the circumcircle of an isosceles triangle \[PQR\] is equal to \[PQ(=PR),\]then the angle P is [IIT Screening 1992; Pb. CET 2004]

    A) \[\frac{\pi }{6}\]

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

    C) \[\frac{\pi }{2}\]

    D) \[\frac{2\pi }{3}\]

    Correct Answer: D

    Solution :

    In \[\Delta PQR,\] the radius of circumcircle is \[PQ=PR\] \[\therefore \] \[PQ=PR=\frac{PQ}{2\sin R}=\frac{QR}{2\sin P}=\frac{PR}{2\sin Q}\] \[\Rightarrow \]\[\sin R=\sin Q=\frac{1}{2}\Rightarrow \angle R=\angle Q=\frac{\pi }{6}\] \[\Rightarrow \] \[\angle P=\pi -\angle R-\angle Q=\frac{2\pi }{3}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner