Vertical and Horizontal Lines
The vertical line is drawn in blue. Notice that the x coordinate of all the points on the blue line is 5.
The horizontal line is drawn in green. Notice that the y coordinate of all the points on the green line is 3.
Parallel lines have the same slope.
Move the slider ‘b’ to see a set of lines that all have the same slope.
Suppose we sit a box that measures 5 by 3 on the x axis as shown below. The diagonal line drawn has slope -5/3.
Rotate the box to see that when a line is rotated a full 90 degrees, the rise and run are interchanged, and a negative slope becomes a positive slope.
In general, if slope of line 1 is
and if slope of line 2 is
then lines 1 and 2 are perpendicular to each other.
Use any method to figure out the equation of the green line so that it goes through the point marked P and is perpendicular to the blue line.
Next Page: Linear Patterns