[br]There's a postulate in Geometry that [color=#0000ff]'two points determine a line.'[br][br][/color]So if you're given two points, just plot them, draw a straight line passing through both points, and your job is done![br][br]In previous exploratory activities, you've probably discovered how to do this.[br][br][i][color=#0000ff]Taking the First Bite[/color][/i] (https://www.geogebra.org/m/ufyfkdr4)[br][i][color=#0000ff]Putting Things in Perspective[/color][/i] (https://www.geogebra.org/m/kxzydnyz)[br][i][color=#0000ff]Getting Off the Grid[/color][/i] (https://www.geogebra.org/m/hqa3etew)[br][i][color=#0000ff]Sharpening Your Tools[/color][/i] (https://www.geogebra.org/m/vjvjqs2z)[br][i][color=#0000ff]Standing at Sword's Point[/color][/i] (https://www.geogebra.org/m/un8uh2zr)[br][br]You can also graph a line by constructing a table of values (at least two ordered pairs), plotting the points, and passing a line through them.[br][br][i][color=#0000ff]Toeing the Line[/color][/i] (https://www.geogebra.org/m/pfkb67ek)[br][br]NOW ... instead of plotting randomly generated pairs of coordinates, you can use two special points—the [i][color=#0000ff]x-intercept[/color][/i] and the [i][color=#0000ff]y-intercept[/color][/i].[br][br]If the intercepts are not already given, you can easily derive them from the [color=#0000ff]STANDARD FORM[/color] of a line [i][color=#0000ff]([/color][/i][color=#0000ff]Ax + By = C) [/color]by using these formulas:[color=#0000ff] x-intercept = C/A[/color][color=#0000ff] and y-intercept = C/B[/color][color=#0000ff].[/color][br][br][i][color=#0000ff]Traveling on the Standard Line[/color][/i] (https://www.geogebra.org/m/chu2bn3u)[br][br]On the top left-hand corner of the applet below, you'll see a linear equation in [color=#0000ff]STANDARD FORM[/color].[br][br]Use the following formulas to fill in the boxes:[br][br][color=#0000ff]slope (m) = -A/B[/color][br][color=#0000ff]x-intercept = C/A[br][/color][color=#0000ff]y-intercept = C/B[/color][br][br]If you type in the correct values and your graph is correct, you'll see a big [i][b][color=#ff00ff]"CORRECT !!!" [/color][/b][/i]sign appear.[br][br]Repeat as many times as needed to master the concept.

[br]The applet below is similar to the one above, except that the boxes for the slope and the intercepts have been left out.[br][br]Move the [color=#0000ff]WHITE DOTS[/color] to graph the [color=#0000ff]x- and y-intercepts.[br][br][/color]If your graph is correct, you'll see a big [i][b][color=#ff00ff]"CORRECT !!!"[/color][/b] [/i]sign appear.[br][br]Repeat as many times as needed to master the concept.

In future lessons, you'll learn how to graph a line on the Cartesian plane using other sets of information. We hope you ENJOYED your GeoGebra adventure!