# How to draw the octahedron

**URL:** <https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599>\
**Category:** Share your creations\
**Created:** [December 25, 2018, 8:27pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599 "2018-12-25T20:27:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [December 25, 2018, 8:27pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599/1 "2018-12-25T20:27:01Z")

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Few days ago was a discussion to draw an octahedron, whwt is inpossibile in Shapr3D.  
Here is a gemetric solution , with draw on face and use subtract tool.  
 ![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/4/4a909ff54f1982fda85c1c65b5703b487eb5ec71.jpeg)  
Need the hatched triangle to subtract from the cuboid.

[https://youtu.be/rRPrfErQki8](https://youtu.be/rRPrfErQki8)  
Brg.  
A

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**Author:** ![tommyn](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tommyn/32/1714_2.png) [@tommyn](https://discourse.shapr3d.com/u/tommyn)\
**Post date:** [December 25, 2018, 8:47pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599/2 "2018-12-25T20:47:51Z")

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Thank you Attila for your contribution/proof. Quite honestly I didn’t understand the negative claim of the other post. Almost like a Christmas troll? Nor did I understand why the approaches shown were not accepted.

Have watched your video once and will have to watch it again so it sinks in.

I had issues in the past doing polyfigures but found a solution when the capability to deform sides/surfaces was introduced. Will take a try at this one.

Discussion and contributions are great. Thanks again…

Best,

Tommy

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**Author:** ![tommyn](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tommyn/32/1714_2.png) [@tommyn](https://discourse.shapr3d.com/u/tommyn)\
**Post date:** [December 25, 2018, 9:13pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599/3 "2018-12-25T21:13:29Z")

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Ok, understand how you did this; elegant!

Is the b = 2R around the square a definitional feature of an octagon? If not, how do you know this? Is b the full diagonal or is it half of the diagonal? Thanks

Best,

Tommy

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**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [December 25, 2018, 10:15pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599/4 "2018-12-25T22:15:53Z")

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Hi Tommy!

a sphere drawn around it: r=a/2xsquare root2  
The diagonal=b=2h=2r=a x squareroot2  
In the octahedron the grinding angles are 90 degree.  
That is why I edit the “h” with tehe outside square radius.  
But most important it was made by geometric and got sharp result infront off the squareroot2 is infinite decimal burst.  
Brg.  
A

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**Author:** ![tommyn](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tommyn/32/1714_2.png) [@tommyn](https://discourse.shapr3d.com/u/tommyn)\
**Post date:** [December 25, 2018, 11:05pm UTC](https://discourse.shapr3d.com/t/how-to-draw-the-octahedron/3599/5 "2018-12-25T23:05:32Z")

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Ok; got it; thanks. A straightforward and elegant solution!

Best,

Tommy