Calculating Altitude Length from Point to Line

[marcus11]

I'm doing math from correspondance, so I have no one to ask.
But to find the length of an altitude from a point to a line, I need to be able to make an equation for a line from 2 sets of quardants.

Thanks.

 

[jim mcnamara]

You want to find $$y=mx+b$$ from two points?

See this page for a step by step explanation:

http://www.webmath.com/equline1.html