# Homework Help: Help Describing Vectors

1. Jan 18, 2005

### vitaly

I am having problems with describing vectors. I understand the part that vectors have magnitude and direction, but that's not the part I'm having issues with. I can't look at a figure and find out whether or not the vector is, for example, 30 degrees south of east or 30 degrees east of south. Does anybody know a good way to find out how to describe vectors? Or maybe a website I could visit to help me?

Thanks.

2. Jan 18, 2005

### MathStudent

I'm sure there are plenty of websites out there, but none come to mind (try a google search).
Descriptions of vectors such as "30 degrees south of east" only give the direction of the vector and tell us nothing about it's magnitude. This can be seen by setting up a cartesian coordinate system with two axis (the typical x-y grid). Label each end of the axis North, South, East, and West (for example the +y direction could be North, +x could be East, the -y south, and -x west). To obtain a vector pointing 30 degrees south of east, start with an arbitrary non zero position vector pointing east ( in the direction of the +x axis ) and rotate it 30 degrees south (that is toward the -y axis). The resulting vector should have an angle of -30 degrees from the +x axis, and based on this coordinate system we call that 30 degrees south of east.