3D Vector Algebra: Dot Product, Cross Product & Orthogonality
In physics, linear algebra, and 3D computer graphics, vector multiplication is defined under two distinct operations: the Dot Product (Scalar Product) and the Cross Product (Vector Product).
Dot Product (Scalar Output)
A · B = AxBx + AyBy + AzBz = |A||B| cos(θ)
Produces a single scalar real number. If A · B = 0, the two vectors are perpendicular (orthogonal at 90°).
Cross Product (3D Vector Output)
A × B = [AyBz - AzBy, AzBx - AxBz, AxBy - AyBx]
Produces a brand-new 3D vector perpendicular (normal) to both input vectors with magnitude equal to |A||B| sin(θ).
Angle Between Two 3D Vectors Formula
θ = arccos[ (A · B) ÷ (|A| × |B|) ]
Where |A| = √(Ax² + Ay² + Az²) and |B| = √(Bx² + By² + Bz²).




