Getting Started With Geometer's Sketchpad
Drawing, Constructing, and Moving Objects

Contents

Using the Toolbox

  Located on the left-hand side of the Geometer's Sketchpad worksheet, you will see a selection of tools that can be used to draw geometrical figures.  
Selection Arrow: Used to select and translate an object. Click and hold mouse button to activate Rotate and Dilate tools.
Point Tool  
Circle Tool  
Line Tool: Creates line segments. Click and hold mouse button to activate Ray and Line tools.
Text Tool: Creates captions or label points and lines.  
Information Tool: Click on objects or menu items for information.  

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Select the circle tool. Move to an empty space on your worksheet, and click and drag outwards to create a circle.

Undoing and Redoing Commands

Go to the Edit menu at the top of the screen. Notice that your first option is Undo Draw Circle, or the last command you completed. Try this. Go back to the Edit menu, and select Redo Draw Circle.

Hold down the Shift key and go back to the Edit menu again. Notice that the first option in the menu is now Undo All. You can use this to revert back to your last saved copy of a worksheet.

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Using the Construct Menu

The Construct menu provides ways to create objects with geometrical properties related to those of objects you have already drawn. Using the Construct menu and the toolbox, draw another circle:
1. Using the point tool , create a point somewhere in a blank space in your worksheet. This will mark the center of your circle.

2. Using the line tool , draw a line segment. This will define the radius of your circle.

3. Activate the selection arrow . 'Select' your line and point simultaneously by clicking on one, and holding down the [shift] key while clicking on the other. Both the point and the line will appear black, indicating that they have been 'selected'.

4. Go to the Construct menu. Notice that some of the items in this menu appear black, indicating that they are available, while other items appear grey, indicating that they cannot be used. Which items are available depends on what types of points, lines, or objects you have selected.

5. From the Construct menu, select Circle By Center + Radius (recall that the two objects you have selected are a center and a radius). A circle will appear on your worksheet.

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Deleting Points and Line Segments

To delete a part of your drawing, simply select it and hit the [delete] key:

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The Status Box

For this next exercise, you will first need to create a triangle inscribed inside of a circle. This means that the three vertices of the triangle will be 'on' the perimeter of the circle. The status box helps you to be sure you position your points exactly where you want them:

1. Create a circle using either of the methods described above.


2. Observe the status box in the lower left-hand corner of the worksheet. This provides information on whatever function you are performing or where your cursor is positioned.

3. Select the line tool, and position your cursor somewhere on the edge of your remaining circle. (Hint: You know you are positioned on the edge of the circle when the status box reads 'From Point on Circle...').

4. Click and drag from one edge of the circle to another to create the first line segment.
5. Move your cursor over an endpoint of the first segment, and observe that the status box reads "From Point ...". Create another line segment starting at this point (the cursor will 'lock' into place when it is close to a point).

6. Create a third line segment from the endpoint of the second segment to the beginning of the first, to complete your inscribed triangle.

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Selecting and Translating Points and Lines

The key feature of Geometer's Sketchpad is that it allows you to change objects that you have created, without having to erase them and draw them over again. Use the selection arrow to select and move points and objects.

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Selecting and Translating Objects

A point is a discreet position on your worksheet. A line segment connects two points together. An object is a collection of points and lines.

There is more than one way to select an object. One way is to '[shift]-click' and select all of the object's components one at a time. Often a quicker way is to draw a selection marquee around the object. To do this, first activate the selection arrow. Then, click on an empty space in the worksheet, and drag to create a rectangle over the object you wish to select.

You will notice that all the points and line segments comprising the selected object will be highlighted.


Now, click and drag on any of the highlighted points or lines.

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Cutting, Copying, Pasting, and Deleting an Object

In much the same way that Microsoft Word lets you cut and paste text and SoundEdit lets you cut and paste sound, Geometer's Sketchpad lets you cut and paste objects. Once you have selected a point, line, or object, you can use the Edit menu to Cut, Copy or Paste the object. To delete an object, you select it and then hit the [delete] key.

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