CK-12 Foundation
Ck 12: Trigonometry: Vector Subtraction
[Free Registration/Login may be required to access all resource tools.] Learn how to subtract two vectors using the triangle method.
CK-12 Foundation
Ck 12: Vector Subtraction
[Free Registration/Login may be required to access all resource tools.] Understand vector subtraction v - w as v + (-w), where -w is the additive inverse of w, with the same magnitude as w and pointing in the opposite direction....
Wolfram Research
Wolfram Math World: Vector Difference
This site defines vector difference. Includes a formula and links to related topics.
National Council of Teachers of Mathematics
The Math Forum: Vector Subtraction
Illustration and description of vector subtraction. Similar to vector addition.