| 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
a circle centered at A and has a radius BC. | 
          
            | 5 |  | Construct
another circle centered at C and has a radius AB. | 
          
            | 6 |  | Generate the
intersection points between the two circles to find the fourth vertex
of the rectangle. | 
          
            | 7 |  | Join
up the four points A, B, C, and D to get the required rectangle. | 
          
            | 8 |  | 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 each two opposite sides
are equal in length.
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