# Straight Line

From the old English "stretched linen" suggesting its origins whereby a piece of string is stretched, chalked and flicked thereby leaving a shadow in chalk of the string in the form of a straight line.

The first two axioms (or postulates) of Euclidian geometry concern straight line segements.

1. A straight line segment can be drawn joining any two points.

2. Any straight line segment can be extended indefinitely in a straight line.

The equation of a straight line in cartesian coordinates is $ax+by=c$

A common transformation of this is $y=mx+c$

One of the Named Curves on this site.