Parallelograms - 2

1. Generate side lengths and angle between.

• Click on the **New Dimensions** button (and wait 2 secs).

REMEMBER: You can always click on (top right) to undo your last action.

2. Construct a parallelogram as in the previous activity with the dimensions just generated.

3. Mark your dimensions.

• Right-click on the base line, click on Properties,

Select "Show Label" and then click on the next to Name and select Value. Hit Enter. You should now see the base length.

• Right-click on one of the sides, click on Properties,

Select "Show Label" and then click on the next to Name and select Value. Hit Enter. You should now see the side length.

• Right-click on the angle, click on Properties,

Click on the next to Name and select Value. Click and drag the size over to 60. Hit Enter. You should now see the angle.

4. Calculate the perimeter of your parallelogram and then click on Show Perimeter to check your work.

Notice that we do not know the height of the parallelogram so we cannot **yet **calculate its area!

5. Draw the height of the parallelogram.

We draw a base line through A and B and then a line passing through our last vertex F and perpendicular to AB. We find the intersection point F of these two lines and then draw a segment from F to G.

• Click on "Line through **2 points**" icon and then click on A and B.

• Click on "Perpendicular line" icon and then click on E and then on the line AB.

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The point G will be drawn!• Click on"Segment through **2 points**" icon and then click on E and F.

6. Clean up

7. Find the height using GeoGebra -otherwise we need trigonometry!

• Right-click on the height, that is on the segment EF and click on Properties, Select "Show Label" and then click on the next to Name and select Value. You should now see the height!

9. Play with your parallelogram.

• Click and drag any blue point (A moves the parallelogram , B rotates the parallelogram). Notice that the **height **never changes since it is completely defined by the length of the two adjacent sides and the angle between them.

• Click on **Reset** to start over.