Q 11-03-133JEE MainJEE Main 2021 (22 Jul, Shift 1)Easy
What will be the projection of vector $\vec A = \hat i + \hat j + \hat k$ on vector $\vec B = \hat i + \hat j$?
Answer: (D) $(\hat i + \hat j)$
The vector projection of $\vec A$ on $\vec B$ is
$$\left(\frac{\vec A\cdot\vec B}{|\vec B|^2}\right)\vec B = \frac{2}{2}(\hat i + \hat j) = \hat i + \hat j$$
(Its magnitude is $\dfrac{\vec A\cdot\vec B}{|\vec B|} = \sqrt2$.)
Solution by Sreeraj P, M.Sc Physics