Q. The point of intersection of $\overrightarrow{\mathbf{r}} \times \overrightarrow{\mathbf{a}} = \overrightarrow{\mathbf{b}} \times \overrightarrow{\mathbf{a}}$ and $\overrightarrow{\mathbf{r}} \times \overrightarrow{\mathbf{b}} = \overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}},$ where $\overrightarrow{\mathbf{a}} = \widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}}$ and $\overrightarrow{\mathbf{b}} = \widehat{\dot{\mathbf{i}}} - \widehat{\mathbf{k}}$ is

A) $3\widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}}$
B) $3\widehat{\dot{\mathbf{i}}} - \widehat{\mathbf{k}}$
C) $3\widehat{\dot{\mathbf{i}}} + 2\widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}}$
D) None of these
Explanation

(a)
The point of intersection of $\overrightarrow{\mathbf{r}} \times \overrightarrow{\mathbf{a}} = \overrightarrow{\mathbf{b}} \times \overrightarrow{\mathbf{a}}$ and $\overrightarrow{\mathbf{r}} \times \overrightarrow{\mathbf{b}} = \overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}}$ is $\overrightarrow{\mathbf{r}} = \overrightarrow{\mathbf{a}} + \overrightarrow{\mathbf{b}}$
$\therefore\ \overrightarrow{\mathbf{r}} = \left( \widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} \right) + (2\widehat{\dot{\mathbf{i}}} - \widehat{\mathbf{k}}) = 3\widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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