National Council of Teachers of Mathematics
The Math Forum: Vector Subtraction
Illustration and description of vector subtraction. Similar to vector addition.
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.
Other
Maths Help: The Scalar Triple Product
This site explains how to multiply three vectors together to produce a scalar triple product.
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: Definition of the Dot Product
Definition of dot product and an application.
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.
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.
Wolfram Research
Wolfram Math World: Perpendicular Vectors
Come to this site to find the transformational matrix to find the vector rotated 90 degrees from the original. The site also states the special relationship between two perpendicular vectors when using the dot product.