## The Geometer's Sketchpad Introductory Lab - page 6

### Mike Riedy

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#### Transformations:

Later we will look at properties of transformations, but for now let's look at the basics.

Start with a new sketch. Draw a triangle and place a single point somewhere outside the triangle.

Describe how you constructed the triangle:

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There is another way to construct a triangle. How?

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Highlight only the single point and choose "Mark Center" under the TRANSFORM menu.

What is the keyboard shortcut for marking center? _________________

You can also accomplish this by double-clicking on the point (a little bullseye should appear around the point for a fraction of a second). Next, change the select tool to the rotation tool (see p. 3). Highlight all parts of the triangle. Drag the triangle.

What happens?

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Change the rotation tool to the dilation tool. Now try dragging the triangle. What happens when you try to move the triangle closer to and farther away from the point?

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The select tool is sometimes called the translate tool. Define the three words translate, rotate, and dilate.

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Start with a new sketch. On the left half of the sketch draw a small smiley face and a vertical line just to the right of it. Feel free to add some color and make your smiley face one solid color. Highlight the line and choose "Mark Mirror" under the TRANSFORM menu. Highlight your entire smiley face and choose "Reflect" under the TRANSFORM menu. Now try moving one of the eyes on the left smiley face.

What happens to the eye on the smiley face at the right?

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Save this sketch on your disk as "Smiley face" (see p. 5 for a review of saving procedures).

#### Animation:

We are now going to play with the coolest function of the Geometer's Sketchpad: animation.

Start with a new sketch. Draw a large circle in the center of your sketch. "Hide" the point that is on the circle.

Now highlight the circle (not the center) and choose "Point On Object" from the CONSTRUCT menu. A new point should appear on the circle. Find its label and change it to "Roger." Highlight Roger and the center of the circle, and have the computer construct a segment connecting the two.

Change the color of this segment to blue, make sure it is highlighted, and choose "Trace Segment" under the DISPLAY menu. Highlight the segment and Roger and choose "Perpendicular Line" under the CONSTRUCT menu. Change the color of the line to red, make sure it is highlighted, and choose "Trace Line" under the DISPLAY menu. Clear all highlighting.

Next, highlight Roger and the circle, in that order. You need to choose "Animation..." from the sub-menu under the choice of "Action Button" under the EDIT menu. Click "Animate". When you do this properly, a button will appear that says "Animate" on it. Double-click the button.

Cool, huh? Click anywhere to stop the animation. Save this sketch on your disk as Animation.