To Place an Unconstrained Arc by Three Points
Select the Place Arc tool ( split button
Set Method to Start, Mid, End.
With no constraints on, enter a data point to define the arc's beginning.
Enter a second data point to define a point on the arc.
Enter a third data point to define the endpoint and sweep angle.
Place unconstrained arc with Method set to Start, Mid, End. Define the start point (1), a point on the arc (2) and the end point (3).
Place Arc, with Method set to Start, Mid, End, and Radius (R), Start Angle (ST) and Sweep Angle (SW) constraints. Place the start point (1) and define the direction (2).