Math Figures Regular Polygon Generator
8 cm6.9 cm

Regular polygons with their apothem and radius

The Regular Polygon Generator draws a regular polygon with 3 to 20 sides, from an equilateral triangle to a 20-gon, sized by its side, its radius or its apothem. Give one of the three and it works out the other two, the interior angle and the central angle.

Draw the apothem to the bottom side and a radius to the bottom right corner to make the right triangle used for area, or every radius to split the polygon into matching triangles. Mark every side and angle as equal, letter the corners, and label the side, angle, apothem and radius with their measures or with x.

What you can set

  • Number of sides: 3 to 20
  • Size from its side, radius or apothem, typed as a number, fraction or square root
  • A label on the sides and the angles, the bottom side and bottom left angle standing for them all, with congruence marks on every one
  • A center dot and its name, the apothem, a radius and all the radii, each solid, dashed or dotted and labeled
  • Corners lettered A, B, C…, a unit, and solved lengths rounded to whole numbers, tenths or hundredths
  • Right-angle squares on or off, a turn, and labels dragged where you want them

Copying, printing and sharing

Copy the figure straight into a test, worksheet or slide, or download it as a PNG or SVG. Printing the page prints just the figure. Share link copies the page’s address with your settings in it, so anyone who opens it sees this exact figure, and presets save settings you use often in your browser. It’s free, with no sign-up.

Example figures

Frequently asked questions

What is the apothem of a regular polygon?

The line from the center to the middle of a side, at right angles to it, and its length. The area of a regular polygon is half its apothem times its perimeter.

Can I size the polygon by its radius or apothem instead of its side?

Yes. Under Size from, pick Side, Radius or Apothem and type its length. The other lengths are worked out and shown faintly in the settings, and any of them can be labeled on the figure.

Which side and angle get the labels?

The side’s label goes on the bottom side and the angle’s in the bottom left corner. Congruence marks go on every side and every angle, to show they are all equal.

What are the polygons past 12 sides called?

The generator names polygons up to the dodecagon (12 sides) and calls the rest by their number of sides, like a 15-gon.

← All math figures