Finding Equations of Horizontal and Vertical Lines

The Problem
Find equations of vertical and horizontal lines passing through the point (8,5). Then graph the lines.

The equation of a vertical line has the form x = k, where k is some number. Since the x-coordinate of the given point is 8, the equation of the vertical line passing through the point is:

x = 8.

In order to graph this line on the calculator, press 2nd, then PRGM [DRAW], and select 4:Vertical. Then press the 8 key and then ENTER, and the line will appear as shown below.

The viewing rectangle was preset to [-10,10,1] by [-10,10,1].

TI83 Calculator Screen TI83 Calculator Screen TI83 Calculator Screen
TI83 Calculator Screen TI83 Calculator Screen

The equation of a horizontal line has the form y = k, where k is some number. Since the y-coordinate of the given point is 5, the equation of the horizontal line passing through the point is

y = 5.

In order to graph this line, press Y = key and enter 5 for y sub one. Now press ZOOM, then select 6:Standard, and the graph should appear as shown below.

TI83 Calculator Screen TI83 Calculator Screen
TI83 Calculator Screen

 


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