Use this procedure to extend fixed tangents to a point of intersection.
Note: You can only perform this procedure when the alignment displays implied points of intersection of two fixed tangents that are joined by a free curve or curve group.
- Select the alignment.
A
grip is displayed at the implied point of intersection. 
- Hover the cursor over the grip.
- From the grip menu, select Solve PI.
The tangents extend to the point of intersection, which now displays a 
grip. 
grip.