| Construction Algorithm | ||
| 1 |  |
Construct a line AB as a given base of the rectangle. |
| 2 |  |
Construct a perpendicular line to AB through the point B. |
| 3 |  |
Construct a point C on the perpendicular line. |
| 4 |  |
Construct M as a midpoint of the diagonal AC. |
| 5 |  |
Define a reflection at the point M, then construct the image of the point B by reflection on M by selecting it to get the fourth vertex D of the rectangle. |
| 6 |  |
Join up the four points A, B, C and D to get the required rectangle. |
| 7 |  |
Switch to drag mode. Pick a free element. Move it around to check your construction. |
| Construction Theorems | ||
| A rectangle is a
parallelogram with a right angle. A parallelogram is a quadrilateral, in which diagonals bisect each other. Reflection preserves the distance between points. |
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