I’m pretty new in graphic design (and Inkscape) and can’t figure out how to draw a unfilled rounded corners isosceles triangle.

What I’m trying to achieve is something like this:

enter image description here

Please notice the rounded corners in the inner side of the triangle and the outer corners.

This is what I got so far, but I can’t figure out how to curve the inner part of the corners:

enter image description here

  • Your rounding radius has to be bigger the corner is sharp because the inner radius becomes 0.
    – joojaa
    May 6, 2017 at 7:45
  • @joojaa Can you explain me how to do it please ?
    – Scotow
    May 6, 2017 at 11:13

2 Answers 2


There are probably a couple of ways to do this. Here's how I would do it.

  1. Draw a triangle with the Create Stars and Polygons tool. Apply a thick stroke (about twice the thickness you need), and apply the rounded corners option in the stroke dialog.

  2. Click Path > Stroke to Path

  3. With the Edit Paths by Nodes tool, select the nodes of the inner path, removing them all, so you are left with one filled outer path.

  4. Remove the fill, and set a stroke thinner than before (thin enough to see the inside corners rounded)

Steps of Edit Illustrated


Draw a triangle. Give to it the wanted wide stroke. You can draw for example a 3 sided polygon holding Ctrl at the same time.

Goto Path > Dynamic offset

Drag the visible node upwards (=to bigger size) until you have also round inner corners. That's said already in a comment, but in a short way.

You can resize the resulted triangle, if it's too big. Resizing without changing the stroke width needs a change in the preferences:

goto Edit > Preferences > Transform, unselect the scaling of strokes.

NOTE: You can't make it arbitarily small because your inner corners will again get sharp as soon as the rounding radius of the outer corners get smaller than the stroke width.

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