Multimedia: Equations of Lines

Eqn of a Horizontal Line
Horizontal Line:
how to find the equation

(1.43M, audio)
Eqn of a Vertical Line
Vertical Line:
how to find the equation

(1.46M, audio)
Eqn of a line, point-slope
Point and Slope:
How to find the equation of a line

(4.13M, audio)
Eqn of a line, two points
Two Points:
How to find the equation of a line

(5.5M, audio)