Use this procedure to model the trunk of the tee fitting. You add the circular geometry, create the profile, and apply an extrusion modifier. 
- To create the trunk of the tee, in the part browser, right-click YZ Plane and click Add Profile 
Circular.  
- Select a center point in the modeling area and specify a second point, or enter 12" (305 mm), to define the radius. 
 
A circular profile is created and is added to YZ Plane in the part browser. 
  
- In the part browser, right-click Modifiers and click Add Extrusion. 
 
- Select the circular profile in the modeling area. 
The Extrusion Modifier dialog box appears. 
  
- Under Termination, select MidPlane for Type, enter 20" (508 mm) for Distance, and click OK. 
 
A cylinder is created to represent the trunk of the tee and an extrusion modifier is added to Modifiers in the part browser.