Getting the chord length of a regular hexagon

Darrien Glasser
2 min readSep 10, 2017

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chord = radius - tan(30) * offset * 2

Woah, hold up, you’re still here? I’m flattered, this is way longer than I would have spent at any site with math explanations.

Getting this formula requires a little bit of work with triangles and trapezoids. Let’s mirror the hexagon across the X axis so everything is upright, and then work with the left portion of chord.

Shoutouts to GIMP for the incredible painting job

Yeah, kind of like that.

Working with regular hexagons gives us a couple of things for free. Let’s break it down.

Regular hexagons all have 120 degree angles, so by cutting the hexagon in half, we know we’re working with a 60 degree angle. If you haven’t noticed or scrolled far enough down yet, you’ll notice there’s a triangle adjacent to our trapezoid.

In case you haven’t noticed the triangle

The length of the chord/2 is the radius - line segment F — H. This is easy to compute, it’s a right triangle. Bring yourself back to high school trig, and the rest is easy.

In case you’ve forgotten, we use TOA, tan(θ) = adj/opp

So that is: tan(30) = offset/segment F — H

Subtract this value from the radius, then multiply it by two, and congrats, you have the chord length.

Q: But Darrien, couldn’t I solve this in 30 minutes?

A: Yeah of course you could, I did, but a Google search is way quicker.

Q: Will this work if I rotate my hexagon 90 degrees?

A: No. You’ll have to use the minimal radius if you want that to work. Throw your radius into this formula, cos(30) * radius and then throw a party.

Q: What about 180 degrees

A: Detention

Have a good day readers.

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