Question

a,b are the magnitude of vectors a bar and b bar . If a bar cross b bar =0 then value of a bar . b bar is

Answer 1

Answer:

The answer is zero.

as A vector cross B vector is given zero so ab =zero.

Now A.B =abcostheta.

so putting the value of of ab, we get A.B to be zero.

Answer 2

Answer:

The value of $\vec{a} \cdot \vec{b}=a b\end{aligned}$.

Explanation:

• Given:

$|\vec{a}|=a and |\vec{b}|=b$

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

$|\vec{a}||\vec{b}| \sin \theta=0$ where $\theta$ is the angle between $\vec{a} and \vec{b} .$

$\begin{gathered}\sin \theta=0 \\\theta=0\end{gathered}$

We have to find

$\vec{a} \cdot \vec{b} &=|\vec{a}||\vec{b}| \cos \theta \\ &=a b \cos 0 \\& \vec{a} \cdot \vec{b}=a b\end{aligned}$

Note: cos0=1.

The value of $\vec{a} \cdot \vec{b}=a b\end{aligned}$.