Diameter
Dimension the diameter of the circle, and arc in the parallel projection. You can change the dimension properties before selecting the element to be dimensioned.

- Select Drawing | Dimensions |  Fast Dimensioning > Fast Dimensioning > Diameter. Diameter.
- Select the dimension properties.  Dimension Properties (2D) Dimension Properties (2D)
- Select an arc or a circle.
- Select Confirm.
Note: 
    
    - Select in the adding of Radius or Diameter dimension the reference line to the the dimension.  Dimension with Reference Line/Simple Dimension Dimension with Reference Line/Simple Dimension
 You can dimension the diameter of a cylinder face by selecting the Dimensions function. Select the cylinder face in the projection between the silhouette lines.
 You can dimension the diameter of a cylinder face by selecting the Dimensions function. Select the cylinder face in the projection between the silhouette lines.

Note: 
    
  - Dimension a thread by selecting the edge of the hole. The thread length is added as a base dimension.

