Q. Area of rhombus is ……., where diagonals are $\overrightarrow{\mathbf{a}} = 2\widehat{\dot{\mathbf{i}}} - 3\widehat{\dot{\mathbf{j}}} + 5\widehat{\mathbf{k}}$ and $\overrightarrow{\mathbf{b}} = - \widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}}$

A) $\sqrt{21.5}$
B) $\sqrt{31.5}$
C) $\sqrt{28.5}$
D) $\sqrt{38.5}$
Explanation

(c)
$Area\ of\ rhombus = \frac{1}{2}\left| \overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}} \right|$
$= \frac{1}{2}\left| \left( 2\widehat{\dot{\mathbf{i}}} - 3\widehat{\dot{\mathbf{j}}} + 5\widehat{\mathbf{k}} \right) \times \left( - \widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}} \right) \right|$
$= \frac{1}{2}\left| - 8\widehat{\dot{\mathbf{i}}} - 7\widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}} \right| = \frac{1}{2}\sqrt{144}$
$= \sqrt{28.5}$

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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