Lines and Axes

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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.
  • Define a parameter t (e. g., t = 3) before entering line g in parametric form using
    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 2.2
  • y(a) the value 3.3
  • z(a) the value -4.4 (because GeoGebra save the line equation as 2.2 x + 3.3 y - 4.4 = 0.

More informations: Coefficients Command

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