From the Toolbar: Find the Circumscribed Polygon (Center-Vertex) Tool icon on the Entity Toolbar (color coded blue) and Click on the tool. The tool is now active and ready for use.

 
From the Shortcut Key: The default shortcut key for the point tool is the letter "Alt + P, 2". Simply press the key and the tool will be activated.

 
From the Command Line: Type "polygon_center_apothem" into the Command Line, at the top of the notification window, and press the Enter/Return key.

1. Click on the drawing to specify the start point, the center point, of the polygon.

2.  Move the mouse and click to specify the end point, an apothem, of the polygon.

Reset:

To draw a polygon using keyboard supplied data open the Tool Tab in the property tree.

1.  Type the center point's coordinates into the "Start Point" 3D Point Property Field found on the Tool Property Tree and press Enter to accept. This will position the center of the polygon.

2.  Type an apothem point's coordinates into the "End Point" field and press Enter to accept. This will place  an apothem of the polygon and finish the polygon drawing process.

Reset:

Right Click: Brings up a Context Menu containing options for this tool.

Use Polyline: Instead of using lines, use a polyline, to draw the rectangle.

Escape (Esc): Cancels current tool and activates the default tool (Selection Tool).

Space: Resets this tool.