7.9.3.7.4. 
Circle tangent to 3 circles
 Circle tangent to 3
    circles [Circle tangent to 3 circles]
Circle tangent to 3
    circles [Circle tangent to 3 circles]
- Activate the tool     Circle tangential to 3 circles [Circle tangent to 3 circles]. Circle tangential to 3 circles [Circle tangent to 3 circles].
 
- One after
        another select the 3 original circles. - -> The
        new circle is inserted tangential to the 3 original circles. 
In the Edit element docking window, you have the option of placing one, two or all three original circles in the tangentially touching circle.