Wolfram Research
Wolfram Math World: Scalar Multiplication
Describes how a scalar can be multiplied to a vector and shows this using diagrams. Site also contains related links, graphs, and pictures.
National Council of Teachers of Mathematics
The Math Forum: Projection: Theory
Describes how to use dot products to project one vector onto another.
National Council of Teachers of Mathematics
The Math Forum: Unit Vectors and Unit Circle
Description of the unit vector and its relationship to the unit circle.
National Council of Teachers of Mathematics
The Math Forum: Vector Addition: Geometry
Illustrates and describes how to add two vectors graphically.
National Council of Teachers of Mathematics
The Math Forum: Dot Products of Non Unit Vectors
Description of finding the formula for the dot product of any two vectors.
Walter Fendt
Walter Fendt: Resultant of Forces (Addition of Vectors)
A short interactive activity which allows you to visualize the sum of vectors.
Educaplus (Jesús Peñas Cano)
Educaplus: Suma Grafica De Vectores
Visualize the sum of different vectors with this interactive activity. You may choose from two to seven vectors.
Wolfram Research
Wolfram Math World: Direction Cosine
This page discusses the direction cosine, which can be used to find the coordinates of a unit vector in the direction of any given vector. Includes some rather advanced formulas.