2. Sample Papers
  3. JEE Main & Advanced

JEE Main & Advanced Sample Paper JEE Main Sample Paper-30

  • question_answer
    If two sides of a triangle ABC are represented by vectors a and \[\left( \vec{a}\times \vec{b} \right)\times \vec{a}\] then maximum value of \[(\sin 2A+\sin B+\sin 2B+\sin 2C)\], is

    A)  1                                            

    B)  \[3/2\]

    C)  2              

    D)  4

    Correct Answer: C

    Solution :

    Vector \[\vec{a}\] and \[(\vec{a}\times \vec{b})\times \vec{a}\] are perpendicular \[\therefore \]Triangle is right angled. \[\sin 2A+\sin 2B+\sin 2C=4\sin A\sin B\sin C\] \[=4\sin A\sin C\] \[=2(cos\,(A-C)-\cos \,(A-C))\] \[=2\cos (A-C)\] \[\therefore \]Maximum value of sin 2A + sin 2B + sin 2C is 2.                     


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