Which direction among the two should we choose for area vector of a plane?

Question

How can we determine the direction of area vector of a plane among the two perpendicular directions to the plane?

I have read in this website that its direction is conventionally determined by right hand grip rule. But how can we apply right hand grip rule to a simple plane?

Answer 1

The convenction usually used is the same as for the cross product of two vectors, i.e. the right-hundle orientation.