Setting Tangency Continuity between curves

1 After starting the Curve Continuity command, in the Degree drop-down list, select Tangency.

2 In the Method drop-down list, choose the method you want to use to apply the change.
 
Fit reference curve applies tangency continuity by modifying only one of the two curves concerned. 
Adjust both applies tangency continuity by modifying both the curves concerned.
Modify common point and adjust both  applies tangency continuity by moving the point where the two curves meet.