Question

Find ????⋅ ???? if |????|=3 , |????|=9 , and the angle between ???? and ???? is π2 radians.

Answer 1

Answer:

$a{\cdot}b=0$

Step-by-step explanation:

It is given that,

Magnitude of a A, $|A|=3$

magnitude of B, $|B|=9$

The angle betwern a and b is $\dfrac{\pi}{2}\ rad=90^{\circ}$

Dot product,

$a{\cdot} b=|a||b|\ \cos\theta\\\\a{\cdot} b=3\times 9\times \ \cos(90)\\\\a{\cdot} b=0$

So, a.b is equal to 0.