To Apply a Point-At Constraint

Select the Constrain Point At Intersection tool.
Select the first construction.
Select the construction with which it is to intersect.
Do one of the following:

Select the point of intersection.

or
Reset to create the point of intersection at the intersection of the two constructions.

The intersection constraint is created next to the point of intersection. An attempt is made to solve and remove two degrees of freedom. The acceptance point determines which solution is selected if there are two solutions or approximately where the solution will be if there is a range of possibilities.