Sketcher > Dimensioning Sketcher Geometry > Working with Dimension Tools > Normal Dimensions > Dimensioning Conics > To Create a Conic Arc Tangency Dimension
  
To Create a Conic Arc Tangency Dimension
1. Click Sketch > Normal or right-click and choose Dimension from the shortcut menu.
2. Click a conic arc.
3. Click the endpoint where the tangency is to be defined.
4. Click the geometry to which the conic arc tangency is defined (such as a centerline or straight edge).
5. Click the middle mouse button to place the dimension.