Projecting distance for Unit Vector

[andykol]

Hello,
I am calculating Unit vector for non orthogonal Cartesian grid. To calculate Unit Vector I need to project eg. y and x distance of east face of cell on i and j axis resp. I am using following formula-
Unit vector= Ue
Surface area= Se=sqrt(dx2+dy2)

Ue=(dy/se)i-(dx/se)j

Can anybody please tell me how I can calculate projection?

 

[HallsofIvy]

How are you defining the inner product?