Comparison of Horizontal and Vertical Lines
y
5
( 0, 4 )
4
( –2, 4 )
Horizontal Line
y=4
3
2
1
( –2, 0 )
x–axis
y=0
x
–3
–2
Vertical Line
x=–2
–1
y–axis
x=0
Horizontal Lines
Vertical Lines
Are oriented East–West
Are oriented North–South
Equation: y = 
Equation: x = 
Horizontal lines have a slope of 0.
Vertical lines have an undefined slope.
Special Horizontal Line:
x–axis which has equation y = 0.
Special Vertical Line:
y–axis which has equation x = 0.