The procedure below describes how to create a new circle from its center. The new circle can also be constrained by additional entities in the graphical display area.
To create a circle from its center:
Select the Circle
tool 
.
The cursor appears in the graphical display
area as a crosshair-and-circle 
.
Click the point in the graphical display area that will be the center of the new circle.
Move the cursor. An image of the new circle appears.
You can define an additional constraint for the new circle.
Move the cursor away from the starting point. The circumference of the new circle expands.
Click to define the new circle.
Tip: Dynamic constraint lines can help you position the new circle relative to points of other entities.