Tip: Creating a Conic Arc Tangency Dimension
For two conic arcs that are tangent to each other at a common point, you need to create only one tangency dimension.
For some end tangency angles, a conic arc cannot be created. For example, it is not possible to make a single conic arc that represents one half or more of an ellipse. If a conic arc fails, modify the tangency angles. If no tangency angles are present, add them, because the problematic tangents must then be determined by adjacent entities.