In the previous tutorials in the **GeoGebra Essentials Series**, we have discussed how to construct *mathematical objects* such as points, lines, line segments, circles and other mathematical objects using the mouse and the tools in the Toolbar. In this post, we learn how to construct these objects using keyboard commands. In particular, we are going to create an equilateral triangle.

**Step by Step Instructions**

In this post, we create equilateral triangle *ABC*. The construction is very similar to GeoGebra Tutorial 2 – Constructing an Equilateral Triangle.

1.) Open GeoGebra. Select **Algebra & Graphics** in the *Perspective *panel to open the *Algebra & Graphics window*.

2.) To plot point * A* with coordinates

**(1,1)**, type

**A = (1,1)**in the Input Bar and then press the ENTER key on your keyboard. Now plot

**B = (5,1)**.

3.) To construct segment * AB*, type

**segment[A,B]**.

4.) To construct a circle with center * A* and passing through

*, type*

**B****circle[A,B]**. Now, construct a circle with center

*passing through*

**B***.*

**A**5.) Now, to intersect the two circles, type **intersect[c,d]. **The names *c* and *d* are the name given by GeoGebra to the two circles (see Algebra view). Names, usually small or capital letters, are given to each object in GeoGebra. Do not confuse the names with equations.

6.) Next, to polygon * ABC*, type

**polygon[A, B, C].**

7.) Now, hide the circles and point * D* by right clicking them and clicking

*Show Object*and we are done. As we can see, we cannot do everything using keyboard commands.

**The GeoGebra Keyboard Commands**

Almost all of the construction tools in the GeoGebra toolbar have keyboard command equivalents. The GeoGebra keyboard commands can be found in the *command list *located at the Input Help window. The Input Help window can be displayed by clicking the arrow at bottom-right of the GeoGebra window (see second figure).

To know about a particular command, get help by selecting it from the command list. When you do this (for example, the command GCD), the syntax will appear at the bottom of the **Input Help** window. You can also click the **Show Online Help** button for additional information.

In GeoGebra, a keyboard command may have more than one syntax. As we can see in the second figure, we can get the GCD of a number using the syntax GCD [<Number>,<Number>] and GCD [<List of Numbers>].

Updated: 23 December 2015 (GeoGebra 5.0)

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