This page introduces simple plotting and graphing in Geogebra
Grid and Axes
open from the view menu
Choose from the view menu options for displaying Axes, Grid and Algebra window. Equations of graphs or geometric objects (like lines and circles) and coordinates of points will be shown in the algebra window and can be easily edited there. If grid but not the axes is turned on, the drawing pad can be used simply as a square paper or geoboard.
open the contextual menu
Setting of axes and grid can be modified by editing the properties of the Drawing Pad. Right click in empty space of the drawing pad and choose from the contextual menu.
In the contextual menu, you can easily choose different ratios of scales on x- and y-axis or zoom in and out with given percentages. There are other means of zooming by using mouse through the zoom mode.
edit the axes
This is the dialog window for editing axes. Setting for x- and y-axis can be edited separately.
edit the grid
This is the section for editing the grid. If distance between grid lines are not specified, it will be adjusted automatically while zooming.
Input of coordinates or equations
Enter via the Input Field
Click inside the input field at the bottom left of the window and start typing coordinates, equations, expressions or other commands.
To plot a point, enter its coordinates. e.g. enter "(2,3)" or "A = (2,3)"
Functions and Equations
To graph a function, simply enter the expression in x or with a function name. e.g. enter "x^3-4x" or "f(x)=x^3-4x" but not "y=x^3-4x"
For conics or lines, you can input a linear or quadratic equation in x and y. e.g. enter "2x+3y=5" or "x^2-3x*y+2y^2=1"
Number and Parameter
Input a number with a name, e.g. "k=1". The letter could then be used to define other objects and treated as a parameter.
e.g. enter "A = (k, k+2)" or "x+k*y=10"
When you click the value k in the algebra window and press the arrow keys, the value of k will be changed and other objects in terms of k will also be updated.
New points can be defined in terms of other points by relating their coordinates. The expressions x(A) and y(A) will be used to represent the x- and y-coordinates of a point A in other commands. In this example, point B is defined in terms of A by entering "B = (x(A)+2, y(A)+1)" in the input field. When A is dragged, B will move accordingly. This can be used to define transformation by means of coordinates. Turn on the traces of A and B to see the effect of dragging.