If are mutually perpendicular, show that Is the converse true?

Given:

, and are mutually perpendicular.

A×B is a vector with its direction perpendicular to the plane containing and .

∴ The angle between

and × is either 0° or 180°.

i.e., =0

However, the converse is not true. For example, if two of the vectors are parallel, then also,

=0

So, they need not be mutually perpendicular.