| Construction Algorithm |
| 1 |
 |
Construct
a line AB as a given base of the parallelogram. |
| 2 |
|
Construct
a point C above the line AB and the line joining B and C. |
| 3 |
 |
Construct a parallel line to AB through point C. |
| 4 |
 |
Construct a circle centered at C and has a radius AB. |
| 5 |
 |
Generate the intersection point between the circle and the line c to find the fourth vertex D of the parallelogram. |
| 6 |
 |
Join up the four points A, B, C and D to get the required parallelogram. |
| 7 |
 |
Switch
to
drag mode. Pick
a free element. Move it around to check your construction. |
| Construction Theorem |
| If two sides of a quadrilateral are parallel and equal in length, then the quadrilateral is a parallelogram. |