Distance between POINT and LINE

I have been playing around with vector stuff for some time but cannot seem to crack this problem
I need to know what the distance is from a point to a line which could be at any angle
In this photo, the length of the GREEN dotted line

Google.
Especially, check this one:
http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/
And for furthermore Geometric problems:
http://local.wasp.uwa.edu.au/~pbourke/geometry/

I found this site quite helpful, as soon as I managed to decipher it ^^

In the code archive are some entries for this problem, for example:

Distance to line

Code archives - Distance to Line segment is just the job. Thanks!