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The Measure MenuUse the Measure menu to calculate geometrical properties of your drawing. When you select an object and go to the Measure menu, available options appear black, and unavailable options appear 'greyed out'. 1. Draw a triangle. 2. Select a side, and measure its length. Using the selection arrow, drag a vertex of the triangle and observe how the length of the segment changes. 3. Simultaneously select the three vertices of the triangle (by [shift]-clicking), go to the Construct menu, and select Polygon Interior. 4. Select the triangle's interior, go to the Display menu, select Color and change the color of your triangle. 5. Select the triangle's interior, go to the Measure menu, and select Area. 6. Drag one of the vertices of the triangle, and watch how the area and side length change. ~~ back to the top ~~ |
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To make your drawings more
presentable, and to be able to communicate effectively as a Geometer, you need
to label your drawings:
1. Select the text tool 
and click on the letter of each of the
three vertices of your triangle. (Hint: use the shift key to select more than
one object.)
2. Click and drag on the new labels to reposition them.
3. Double click on each label to edit them. Change the names of your endpoints to "A", "B", and "C".
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In Geometry, a convention has been established for naming angles. For
example, the angle B in this drawing could be called either angle ABC or angle
CBA. Geometer's Sketchpad uses this same naming convention.
In
this figure we can see why such a naming convention is important. If you refer
to angle B in this drawing, which angle are you refering to, angle ABC, or angle
CBD? These are different angles!
Measure one of the angles in your drawing:
1. Using the selection arrow, select the endpoints A, B, C in exactly that
order. (Hint: use the shift key to select more than one object.)Go to the
measure menu, and select Angle. This gives you the measurement of angle
ABC.
2. Drag the vertex C, and watch how this affects angle ABC. Try dragging C until
you get an angle measurement of 90 degrees.
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Write the word 'GEO':
1. To make the letter 'G', use the point tool to create the endpoints
of the letter, and then go to the Construct menu and select Segment.
If there is an extra segment, you may need to select and delete it.
2. Make the letter E using the line tool. Use the select tool
to highlight all points and segments at the same time. Use the status box
to make sure that the line segments connect.
3. Make the letter O using the circle tool.
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Select the center of the circle you used to create the letter 'O'. Go to the Display menu, and select Hide Point. Does anything happen to the rest of the circle? How does hiding an object differ from deleting an object (if you can't remember, draw another circle, select the center, and hit [delete])?
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Using Geometer's Sketchpad, it is possible to create figures as if you were using a straightedge. First, make some measurements of the letter 'E' that you created.
1.
Select the two points of your letter E shown. Go to the Measure menu,
and select Distance.
2.
Select two more points of the letter E shown. Go to the Measure menu,
and select Distance. Are these two distances exactly equal? It most cases
they will not be.
Create another letter 'E', in the following manner:
1. Using the line tool, create the vertical backbone of the letter 'E'.
2. Select the line, go to the Construct menu and select Point at Midpoint.
3. Make measurements of the same two line segments as in the exercise above.
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1. Select part of your
drawing by using the selection arrow tool to create a selection marquee.
2. Go to the Edit menu and select Copy.
3. Open up Microsoft Word.
4. Position your cursor somewhere on your Word document, and select Paste
from the Edit menu.