I want to find the exact positions (XY coordinates) of the start and end points (circled in brown) of an arc. I think Inkscape treats line drawings differently from circles and arcs, resulting in the position indicator (underlined in red) being greyed out. But I want the arc to line up with another line I have (as shown), and the lack of positions make the exact alignment a rather cumbersome process.

Is there any method (either via settings or via an extension) to display the positions?