The coordinate plane defined with description of x,y axis, quadrants, origin.
Math Open Reference

How to determine if lines are parallel in coordinate geometry
Math Open Reference

Introduction to the concept of lines in coordinate geometry.
Math Open Reference

Definition of a line when the defining points are on the coordinate plane
Math Open Reference

Introduction to coordinate geometry.
Math Open Reference

Determining where two straight lines intersect in coordinate geometry
Math Open Reference

How to find the intercept of a line, given the coordinates of two points on the line
Math Open Reference

Definiton and equation for a horizontal line in coordinate geometry
Math Open Reference

Definiton of the equation of a straight line, in 'point  slope' form: y = m(xPx) + Py
Math Open Reference

Definiton of the equation of a straight line, in 'slope and intercept' form: y = mx+b
Math Open Reference
