Tests for Parallelograms
First, turn on your TI-84 and press the APPS key. Arrow down until you see Cabri Jr and
press ⊆. You should now see this introduction screen.
To begin the program, press any key. If a drawing comes up on the screen, press the ο
key (note the F1 above and to the right of the key – this program uses F1, F2, F3, F4, F5
names instead of the regular key names) and arrow down to NEW. It will ask you if you
would like to save the changes. Press the ψ key and then enter to not save the changes.
A parallelogram is a quadrilateral where opposite sides are
parallel. One way to look at this is to say that the distance
between opposite sides is always the same, where the distance
refers to the length of a line segment which is perpendicular to
opposite sides. To test this, start with a parallelogram.
Place a point on side AB. Construct a perpendicular to AB and
find the point of intersection of this line with side CD.
Hide the perpendicular line and construct a line segment
connecting the two points. Measure the length of this line
segment.
If you drag the point on AB, the line segment should remain the
same length. Test the perpendicular distance for the other pair of
sides as well. You may have to construct lines through AD and
BC in order to test this.
