Show that `veca.(vecbxxvec c)` is equal in magnitude to the volume of the parallelpiped formed by the vectors `veca,vecb and vec c`

Explanation

Let a parallelopiped be formed on the three vectors `vec(OA)=veca, vec(OB)=vecb`
and `vec(OC)=vec c`Now, `vec(b)xxvec(c )=bc sin 90^(@) hat (n)=bc hat(n)`
where `hat(n)` is unit vector along `vec(OA)` perpendicular to the plane containing `vec(b) " and " vec( c)`.
Now `vec(a)(vec(b)xx vec (c ))=vec(a). " bc" hat(n)`
which is equal in magnitude to the volume of the parallelpiped.