2. Solved Papers
  3. JAMIA MILLIA ISLAMIA

JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2011

  • question_answer
        Let\[u,\text{ }v,\text{ }w\]be such that\[|u|=1,|v|=2,|w|=3\]If the projection v along u is equal to that of w along\[u\]and\[v,\text{ }w\]are perpendicular to each other, then\[|u-v+w|\]equals to

    A)  \[\sqrt{14}\]                                     

    B)  \[\sqrt{7}\]

    C)  \[2\]                                    

    D)  14

    Correct Answer: A

    Solution :

                    Given, \[|u|=1,|v|=2|w|=3\] \[\therefore \]  \[\frac{v.u}{|v|}=\frac{w.u}{|u|}\] \[\Rightarrow \]               \[v.u=w.u\]and\[u.w=0\] Now, \[|u-v+w{{|}^{2}}={{u}^{2}}+{{v}^{2}}+{{w}^{2}}-2u.v\]                                                             \[+2u.w-2v.w\] \[=1+4+9-2\text{ }v.w=\text{ }14-0=14\] \[\therefore \]       \[|u-v+w|=\sqrt{14}\]


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