Difference between revisions of "Lines and Axes"
From GeoGebra Manual
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{{example|1=<br/> | {{example|1=<br/> | ||
* Type in <code>g: 3x + 4y = 2</code> to enter line g as a linear equation. | * Type in <code>g: 3x + 4y = 2</code> to enter line g as a linear equation. | ||
− | * | + | * You can enter a line in parametric form thus: <br><code>g: X = (-5, 5) + t (4, -3)</code> |
* Define the parameters m = 2 and b = -1. Then, you can enter the equation<br><code>h: y = m*x + b</code> to get a line h in y-intercept-form.}} | * Define the parameters m = 2 and b = -1. Then, you can enter the equation<br><code>h: y = m*x + b</code> to get a line h in y-intercept-form.}} | ||
==Axes== | ==Axes== | ||
The two coordinate axes are available in commands using the names ''xAxis'' and ''yAxis''. | The two coordinate axes are available in commands using the names ''xAxis'' and ''yAxis''. | ||
{{example|1=The command <code>[[PerpendicularLine Command|PerpendicularLine]][A, xAxis]</code> constructs the perpendicular line to the x-axis through a given point A. }} | {{example|1=The command <code>[[PerpendicularLine Command|PerpendicularLine]][A, xAxis]</code> constructs the perpendicular line to the x-axis through a given point A. }} |
Revision as of 14:11, 12 September 2011
Lines
You can enter a line as a linear equation in x and y or in parametric form into the Input Bar. In both cases previously defined variables (e. g. numbers, points, vectors) can be used within the equation.
Note: You can enter a line’s name at the beginning of the input followed by a colon.
Example:
- Type in
g: 3x + 4y = 2
to enter line g as a linear equation. - You can enter a line in parametric form thus:
g: X = (-5, 5) + t (4, -3)
- Define the parameters m = 2 and b = -1. Then, you can enter the equation
h: y = m*x + b
to get a line h in y-intercept-form.
Axes
The two coordinate axes are available in commands using the names xAxis and yAxis.
Example: The command
PerpendicularLine[A, xAxis]
constructs the perpendicular line to the x-axis through a given point A.Comments
Get parameters of a line[edit]
From the line a: 2.2 x + 3.3 y = 4.4
you'll get with
x(a)
the value 2.2y(a)
the value 3.3z(a)
the value -4.4 (because GeoGebra save the line equation as2.2 x + 3.3 y - 4.4 = 0
.
More informations: Coefficients Command