Does anyone know how to draw a curve of a specified radius connecting two previously drawn line ends? In this instance I don't know the location of the center point. The attached drawing shows the issue. The smaller sketch shows the four possible ways that a curve of a given radius could be drawn through a pair of points.
For that matter, suppose I wanted any entity, such as an ellipse, to pass through these line ends. Is there a way to pre-draw the shape, then move it and snap it to the line endpoints?
On your first question, draw two circles of your desired radius with centers on those line ends. The intersection is the center of your desired arc. Then just use the center-and-2 points arc tool. The delete your two circles.
Your second question seemed to conflict with itself. If you have the finished desired entity created (= it has end points) then just use the translate tool (a very powerful/versatile tool) to move it's end point to the other end point.
If it doesn't have end points then your solution depends on the particulars. In the case of a complete ellipse, your problem is indeterminate.....i.e. it has an infinite number of solutions. .