# If → a = 2 ^ i + ^ k , → b = ^ i + ^ j + ^ k , find the magnitude of → a × → b . - Mathematics

Sum

If $\vec{a} = 2 \hat{ i } + \hat{ k } , \vec{b} = \hat { i } + \hat{ j } + \hat{ k } ,$  find the magnitude of  $\vec{a} \times \vec{b} .$

#### Solution

$\text{ Given } :$
$\vec{a} = 2 \hat{ i } + 0 \hat{ j } + \hat{ k }$
$\vec{b} = \hat{ i } + \hat{ j } +\hat{ k }$
$\vec{a} \times \vec{b} = \begin{vmatrix}\hat{ i } & \hat{ j } & \hat{ k } \\ 2 & 0 & 1 \\ 1 & 1 & 1\end{vmatrix}$
$= \left( 0 - 1 \right) \hat{ i } - \left( 2 - 1 \right) \hat{ j } + \left( 2 - 0 \right) \hat{ k }$
$= - \hat{ i } - \hat{ j } + 2 \hat{ k }$
$\Rightarrow \left| \vec{a} \times \vec{b} \right| = \sqrt{\left( - 1 \right)^2 + \left( - 1 \right)^2 + 2^2}$
$= \sqrt{6}$

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#### APPEARS IN

RD Sharma Class 12 Maths
Chapter 25 Vector or Cross Product
Exercise 25.1 | Q 2.2 | Page 29