Vector Dot Product Calculator

Vector A

Vector B

Understanding Vector Dot Product

What is a Vector Dot Product?

The dot product (scalar product) of two vectors is defined as the product of their magnitudes and the cosine of the angle between them:

A · B = |A| |B| cos(θ)

Or in component form:

A · B = AxBx + AyBy + AzBz

where:

  • A and B are vectors
  • |A| and |B| are vector magnitudes
  • θ is the angle between vectors
  • Ax, Ay, Az are components of vector A
  • Bx, By, Bz are components of vector B

Properties of Dot Product

Key Properties:

  • Commutative: A · B = B · A
  • Distributive: A · (B + C) = A · B + A · C
  • Scalar Multiplication: (kA) · B = k(A · B)
  • Self Dot Product: A · A = |A|²

Special Cases:

  • Parallel vectors (θ = 0°): A · B = |A| |B|
  • Perpendicular vectors (θ = 90°): A · B = 0
  • Opposite vectors (θ = 180°): A · B = -|A| |B|

Geometric Applications

Finding Angles Between Vectors

θ = arccos((A · B)/(|A| |B|))

Vector Projection

proj_B A = ((A · B)/|B|²)B

Work in Physics

W = F · d = |F| |d| cos(θ)

Applications in Computer Graphics

  • Surface Normal Calculations
  • Light Intensity: I = L · N
  • Shadow Calculations