If the angle between the vectors `vecA and vecB` is `theta,` the value of the product `(vecB xx vecA) * vecA` is equal to

Options

A. zero
B. `BA^(2) sin theta`
C. `BA^(2) cos theta`
D. `BA^(2) sin theta cos theta`

Answer

A

Explanation

(a): `vecA.vecB=AB cos theta`
The cross product of `vecB and vecA` has direction normal to plane of `vecA and vecB`
So, `(vecBxxvecA).vecA=(BA sin theta) vecn.vecA`
`=(B A sin theta). Sin A cos 90^(@)`
=0