Course: Trigonometry
Topic: Vectors
Subtopic: Dot Product


In that "product" means to multiply, dot product is an operation that is one way to multiply two vectors. (The other is cross product which is only performed on two 3D vectors.) There are two ways to perform the dot product, i.e. two different, but connected, dot product formulae. The result from the dot product has algebraic and geometric interpretations.


By the end of this topic you should know and be prepared to be tested on:


Terms you should be able to define: dot product, orthogonal

Dot Product Formulas:
`vecu`•`vecv = <<a,b>>`•`<<c,d>> = ac+bd`
`vecu`•`vecv = ||vecu||*||vecv||*costheta`

Mini-Lectures and Examples

STUDY: 2D Vectors - Algebraic Approach, Dot Product

Supplemental Resources

Calculating the dot product manually is not difficult, but if you want to do so electronically I have directions for Texas Instruments calculators TI-86, TI-89, and TI-92 here: Prof. Keely's Calculator Guide: Vector Products.

For a visual understanding of what the dot product means geometrically explore this Java applet: www.falstad.com/dotproduct

rev. 2020-11-05