Question

Vector $\overrightarrow{A}$ has a magnitude of $5$ units, lies in the $xy$ - plane and points in a direction $120^{\circ }$ from the direction of increasing $x$ . Vector $\overrightarrow{B}$ has a magnitude of $9$ units and points along the $z$ -axis. The magnitude of cross product $\overrightarrow{A}\times \overrightarrow{B}$ is

• A. 30
• B. 35
• C. 40
• D. 45

Answer 1

Answer: (D)

$|A|=5,|B|=9$
Vector $B$ makes angle $90^{\circ }$ from $A$

$A\times B=|A||B|\sin \theta$
$=5\times 9\sin 90^{\circ }$
$=45$