## Geometer’s Sketchpad Essentials 4 – The SSS Triangle Congruence

This is the fourth part of the Geometer’s Sketchpad Essentials Series. In this tutorial, we are going to construct another triangle which is congruent to a given triangle using the concept of the SSS triangle congruence.  Recall that the SSS congruence theorem tells us that two triangles are congruent, if their corresponding sides are congruent. In doing the construction, we are going to learn how to use the Ray tool, the Circle tool, and other commands.

1.) Construct triangle ABC.

2.) Next, we construct ray DE.  To do this, click the Straightedge tool box and hold the mouse button to display the other tools. Now, choose the Ray tool.

3.) Click two distinct points on the sketch pad and display the names of the two points. Your sketch should look like the first figure. 4.) Next, we will construct a segment DF which is congruent to AC. To do this, be sure to deselect all the objects by clicking on the vacant part of the sketch pad. Select point D, then select segment AC (do not select the points!), click the Construct menu, and then click Circle By Center+Radius. This will produce a circle with center D and radius equal to the length of AC. » Read more

## Geometer’s Sketchpad Essentials 3 – Constructing an Incircle

This is the third part of the Geometer’s Sketchpad Essentials Series. In this tutorial, we are going to construct the incircle of a triangle. In doing so, we are going to learn how to use the Compass tool and construct Angle bisectors.

Step by Step Instructions

1.) Using the Segment tool, construct a triangle.

2.) Select the Text tool and click each vertex to reveal their names. GSP will name the triangle ABC.

3.) To construct the angle bisector of angle A, deselect all the objects, and then click the vertices in the following order: B, A, C (or C, A, B).

4.) Next, click the Construct menu from the menu bar and choose Angle Bisector. This will produce a ray bisecting angle ANow, construct the the angle bisector for angle B.

5.) To intersect the two rays, deselect all the objects, click the two rays, and choose Intersection from the Construct menu. The intersection of the two rays will be the center of our circle.  » Read more

## Introduction to the Geometer’s Sketchpad

This is the first part of the Geometer’s Sketchpad Essentials Series.  In this post, we will learnabout Geometer’s Sketchpad and its environment before we use the software.

Geometer’s Sketchpad (GSP) is a commercial geometry software created my Nicolas Jackiw in the 1980s. It is similar to GeoGebra, but with fewer tools. On the one hand, it is more difficult to construct geometric objects using GSP compared to other dynamic geometry software; but, on the other hand, it can be inferred that because of the lack of tools, it may improve geometric construction knowledge better than many geometry software.

The Geometer’s Sketchpad (version 4.07) window is shown in the figure below. For now, we will be using this version in our tutorials (I have not bought a new version yet).  However, all of the tutorials in this series are also compatible with the latest version (version 5). » Read more

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