When two vectors are perpendicular their cross product is zero?

No, when two vectors are perpendicular, their dot product is zero, not their cross product. The cross product of two vectors is a vector that is orthogonal (perpendicular) to both of the original vectors. The magnitude of the cross product represents the area of the parallelogram formed by the two vectors, and the direction of the cross product follows the right-hand rule.

In mathematical notation, if two vectors A and B are perpendicular, their dot product is zero:

A ⋅ B = 0

On the other hand, the cross product of two perpendicular vectors is not necessarily zero. The cross product of perpendicular vectors will have a magnitude equal to the product of the magnitudes of the two vectors and will be perpendicular to both of them.