Question

Magnitude of vector $3\hat{i}-12\hat{j}-4\hat{k}$

• A. 13
• B. $\sqrt{13}$
• C. 19
• D. none

Answer 1

The correct option is A 13

Let $a=3\hat{i}-12\hat{j}-4\hat{k}$

Magnitude of a,$\left|a\right|$ =$\sqrt{3^2+(-12{)}^2+(-4{)}^2}$

$=\sqrt{9+144+16}$

$=\sqrt{169}$

$=13.$