Surfacing > Creating Advanced Surface Features > Creating Boundary Blends > Tip: Working with Antitangent and Tangent Boundaries
  
Tip: Working with Antitangent and Tangent Boundaries
You can create a boundary blend surface between two antitangent boundaries. The following figure shows two antitangent curves, trimmed at a common point. Notice that the angle between tangency vectors of the two curves is 180º.
1. Tangency vector of Curve A
2. Tangency vector of Curve B
3. Curve A
4. Curve B
5. 180º
Specifying tangency conditions for both antitangent boundaries may create contradictory constraints for the resulting geometry. As a result, the feature may fail or produce a surface that does not comply with the specified tangency conditions.
A blended surface feature cannot be created when bounding curves become tangent to each other.