Center-Point rectangle
The Center-Point Rectangle 
tool is used to draw a rectangle by specifying its center and one corner.
Using the mouse
The first click of the left mouse button sets the center point of the rectangle.
The second click sets a corner point, which defines the width and height from the center.
Using the keyboard
Type in the Center point and the Corner point into the input boxes, and press Enter to draw the rectangle.
You can use either Absolute or Relative methods to specify coordinates.