Question

If |a| = 13, |b| = 5 and a.b = 60, then find |a × b|.

Answer 1

Answer:

$\vec a\times\vec b=0$

Step-by-step explanation:

As we know that

$\vec a.\vec b=|\vec a||\vec b|\:cos \theta$

So here |a| = 13, |b| = 5 and a.b = 60

$60=13(5)\:cos\:\theta\\\\cos\:\theta=\frac{60}{60} \\\\ cos\:\theta=1\\\\ \theta=cos^{-1} (1)\\\\ \theta=cos^{-1} (cos 0)\\\\\theta =0$

the vector product is given as

$\vec a\times\vec b=|\vec a||\vec b|\:sin \theta$

since sin 0=0

So,$\vec a\times\vec b=0$