How to calculate the radius of a circle inscribed inside a triangle

[Anonymous]

Requesting a little assistance please.
I have a equilateral triangle. The length of the sides is 0.012014. How do
I calculate the radius?

Sincerely,
Mathematically Challenged Mel

[Anonymous]

Wikipedia has some info (and links) on the topic.

http://en.wikipedia.org/wiki/Triangle_Centroid

For equilateral I think it would be:

(cos(30)*S)*(1/3) where S is the length of the side

HTH,

Gary

[Anonymous]

Thanks.

I got:
radius = 0.0069362861

The formula I used is (0.012014 * (Sqr(3)) / 3).
I hope that's right 😉



"Gary McMaster" wrote in message
news:5312821@discussion.autodesk.com...
Wikipedia has some info (and links) on the topic.

http://en.wikipedia.org/wiki/Triangle_Centroid

For equilateral I think it would be:

(cos(30)*S)*(1/3) where S is the length of the side

HTH,

Gary

[Anonymous]

0.0069362861

I get very close to that for the diameter (confirmed with Acad layout)

[Anonymous]

Here are 2 methods using your data:

As Gary showed:
cos(30) * 0.012014 / 3 = 0.003468143

Or:
tan(30) * 0.012014 / 2 = 0.003468143

"Mel" wrote in message
news:5312866@discussion.autodesk.com...
Thanks.

I got:
radius = 0.0069362861

The formula I used is (0.012014 * (Sqr(3)) / 3).
I hope that's right 😉



"Gary McMaster" wrote in message
news:5312821@discussion.autodesk.com...
Wikipedia has some info (and links) on the topic.

http://en.wikipedia.org/wiki/Triangle_Centroid

For equilateral I think it would be:

(cos(30)*S)*(1/3) where S is the length of the side

HTH,

Gary

[Anonymous]

There is a simple way in AutoCAD. Draw a line from a corner of the triangle
to its opposite edge, similarly for the other 2 corners. You'll have an
intersection of the three lines at center of triangle.

Distance from the intersection point to the edge is the radius of circle
inscribed inside the triangle.
Distance from the intersection point to the corner is the radius of circle
circumscribed about the triangle.

---
T.W.Tan