A Construction
of a Parallelogram
Using Geometer's Sketchpad
by David
Wise
Note: I recommend that this page be printed out, so that the
instructions are easier to follow.
Definition: A parallelogram
is a quadrilateral whose opposite sides are parallel.
Click here to link to a new GSP sketch to complete a construction
of a parallelogram.
When completing a construction, use the definition
as a guide.
- Construct two points, A and B.
- Construct line AB.
- Construct point C, not on line AB.
- Construct line BC.
- Select point C and line AB and construct
a parallel line to line AB.
- Select point A and line BC and construct
a parallel line to line CB.
- Construct the intersection point of the two
lines.
- Construct the segments AB, BC, CD, DA.
- Select and hide the original lines.
- Click and drag any vertex and/or side to
make sure that your construction always holds true for the definition
of a parallelogram.
- Using the selection tool, click and drag
around your constructed parallelogram, so that the entire parallelogram
is selected. Use the work menu to create
a script.
Using only the definition of a parallelogram,
what measurement of the sides of a parallelogram must be used
to support the claim that your construction is of a parallelogram?
If you have any questions while trying to complete this investigation,
or suggestions that would be useful, especially for use at the
high school level, please send e-mail to esiwdivad@yahoo.com.
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the Table of Contents.