Can I draw an arc tangent to two circles?


Hi everybody.

I’m trying to do the shape related to this exercise:

But I’m having problems drawing the arc tangent to the two circles.
I’ve tried two ways:

  1. Drawing a guideline 72mm size from the top of the big circle as reference and then drawing the arc.


  1. Drawing an arc with 72mm radius and then trying to snap it to the top of the big circle.
    EDIT: I uploaded the same image twice, now it’s ok.

I had no success with any of the methods I tried, I’m probably doing something wrong.

This is my skp: EjerBas05.skp (33.0 KB)

Thanks in advance.


I think this is my best try but it’s still not perfect. Radius is 66,91 to make it match.



Look at
It has various tools to make ‘true’ tangents, fillets etc, and sidestep the limitations of SketchUp’s segmented circles/arcs…


Thank you so much.
I’m going to try it.
I knew about your extension and I also tried but I probably chose the wrong option.
I’m going to try it again, I will let you know if I’m not able to do it by myself.


I give up xD


Why ?


The extension is awesome and offers more than I probably could need , but I don’t find any way to draw that arc using it.
I tried it with tangential arcs, [arc+line] but I didn’t get it. In fact, I think I tried all possibilities.


Can you attach a simple SKP of what you have so far, so someone might help ?


Have a look at this video.

EjerBas05_ecati.skp (33.3 KB)

How to draw a circle circumscribed and tanger to other two

Thank you so much guys.
@TIG let me record a video and upload it to youtube. I will show you what I tried.
@ecati it worked like a charm.


I probably will regret showing this video, but this more or less almost everything I tried (I tried more combinations).
I just upload it to show you that I tried it, I very thank you all the help you offer to me and I understand I also have to try it by myself with some pieces of advice.

If you want me to share some .skp I don’t know which one to upload, I think the one in the first post is the one still not messed up at all.
EDIT: I also tried it with circunferences that are not intersecting but with no success and with a circle and a line.

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