How do I draw a line a particular distance from a point (not an offset)?

Hello, I’m new to SketchUp, but not AutoCAD. Perhaps I just don’t know the right lingo, because I can’t find anything in the community or help topics…
I’m drawing a floorplan. I’d like to draw a vertical line that starts 15’ from a corner. I don’t want to offset the line that makes the corner–the new line will be shorter. I see the inference tag that says "from point"when I hover over the corner and move the direction toward where I want to start the line. What do I do from there? I haven’t used it in a while, but in AutoCAD, I would type @15’ and that would be the start point of the new line.
Thank you!

Fastes way: draw a temporary line and delete it afterwards.

Hey there, I’m about a (heavy duty) month into Sketch Up also, after 10+ years in AutoCad. I’m surprised too, that there is not a command that approximates the SNAP FROM feature in ACAD. For anyone not familiar, it lets you start a line, say, two inches along one that’s already established, or end a line a foot from the point or line you are approaching. You can set a circle center three inches along the x axis from a given object, etc. While this can be done with guide lines or guide points or construction lines to be erased after, it is much more time-consuming and clunky. With SNAP FROM, it’s start a line, click SNAP FROM, click the point you’re referencing, type the distance, return. In a typical drawing, I use it hundreds of times.
Is this the kind of thing that would be ruby-scripted? It seems there are some very clever work-around extensions available, like mirror, which lets you mirror an object or objects off of a mirror line or point of your choosing (you can do this in acad natively).
Sketch Up seems to be a great modeling program, and I’m loving learning it. It is a very different way of approaching drawing than that with which I’m familiar, and I know part of learning a new program is learning to think and organize in that program’s way of thinking. But SU seems to be crying out for a SNAP FROM command. The inferencing in Sketch Up (which is fantastic), seems ready to incorporate such a feature.
Thoughts?
Thanks!

You may be able to get a similar effect entering relative coordinates in the Measurement box. See https://help.sketchup.com/en/article/3000090 which describes how to enter coordinates as relative or absolute.

To elaborate on my previous reply…

I’ve drawn two walls at the corner of a room about 20’ square, and made them into a component (or you could use a group).

Draw a line in the corner vertical of the height you want (outside the context of the walls).

Select the Move tool, pick its bottom end, then to move it enter the relative coordinate of the point you want to move it to - for example, <-10',-6',0> (you need three coordinates, and I assume here you want the end of the line on the floor, at z=0).

Like this: