Objects creation and modification	Drawing geometric objects
Drawing circles
Overview     Operations     Commands

It is possible to create circles in several ways. The default method is to specify the center and the radius.
It is also possible to use two points defining the diameter or three tangent points.

Drawing a circle tangent to other objects

The tangent point is a point in which an object touches another object without intersecting it. To create a circle that is tangent to other objects, select the objects and then specify the radius of the circle.

It is also possible to create a circle tangent to three points, specifying the three points on preexisting elements, near the desired tangent points.

Also see:

Using the object Snap