What is the math for making a diamond that will make an 8-pointed star?
#1
What is the math for making a diamond that will make an 8-pointed star?
I'm math challenged... I want to make an octagon using triangles (that point toward the center of the octagon), then mirror image the triangle (so it becomes a diamond), and have a resulting star. How do I figure out what the length of the sides of the triangles should be? The short side of the triangle will make the octagon, and the other two sides of the triangle will be equal and longer. If I make the short side of the triangle, for example, 6", then what will be the length of the other two sides?
#2
I'm math challenged... I want to make an octagon using triangles (that point toward the center of the octagon), then mirror image the triangle (so it becomes a diamond), and have a resulting star. How do I figure out what the length of the sides of the triangles should be? The short side of the triangle will make the octagon, and the other two sides of the triangle will be equal and longer. If I make the short side of the triangle, for example, 6", then what will be the length of the other two sides?
its not so much about the length, as it is about the angles in the centre. An (imaginary) circle in the middle uses 360 degrees. To get 8 sections you divide 360 by 8. This gives you a centre angle of 45 degrees for each section of your octagonal shape.
You probably have a 45 degree triangle ruler already lol.
With this angle you can then go ahead and make your sides whatever you need them to be, provided you keep both sides the same. The third length across the outside will sort itself out.
Try it out with a bit of paper first :-))
If you want a 5-pointed star you'd divide 360 by 5.
6-points, divide 360 by 6
Etc........
#5
Siodach, Thanks! That's just the info I wanted. :-) In the meantime, I also found these nifty calculators: https://rechneronline.de/pi/octagon.php
http://www.htmliseasy.com/octagon_layout/
http://www.htmliseasy.com/octagon_layout/
Last edited by givio; 02-06-2016 at 12:25 PM.
#6
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Join Date: Aug 2010
Location: Piedmont Virginia in the Foothills of the Blue Ridge Mtns.
Posts: 8,562
She never mentioned HSTs. I'm sure she was thinking either isosceles or equilateral triangles; this whole topic is an interesting one. Good thing we have the brilliant Scot among us!
Love your name, Siodach. Please tell us how it is pronounced.
Jan in VA
#7
jan is correct in that HSTs wouldn't do in this instance, because the two sides coming away from the 45 degree point are NOT equal in length in a HST and they need to be equal in Givio's design.
I don't know about brilliant, but I was born in England and came to Scotland in 1972, so regard myself as a naturalised scot by now lol.
SIODACH is a Gaelic word, pronounced (as close as I can get lol) 'shuh-da-cchh', where the cchh is soft at the back of your throat as in 'loch' .
It means 'silky', particularly as a description of hair, and dates back to the time when I bred Persian cats. Siodach was/is my cattery name (and it will remain mine until 50 years after my death, he he). The word has the great advantage that if I want to sign up for something, that name has never been already taken lol.
#8
Super Member
Join Date: Aug 2010
Location: Piedmont Virginia in the Foothills of the Blue Ridge Mtns.
Posts: 8,562
Hi there
jan is correct in that HSTs wouldn't do in this instance, because the two sides coming away from the 45 degree point are NOT equal in length in a HST and they need to be equal in Givio's design.
I don't know about brilliant, but I was born in England and came to Scotland in 1972, so regard myself as a naturalised scot by now lol.
SIODACH is a Gaelic word, pronounced (as close as I can get lol) 'shuh-da-cchh', where the cchh is soft at the back of your throat as in 'loch' .
It means 'silky', particularly as a description of hair, and dates back to the time when I bred Persian cats. Siodach was/is my cattery name (and it will remain mine until 50 years after my death, he he). The word has the great advantage that if I want to sign up for something, that name has never been already taken lol.
jan is correct in that HSTs wouldn't do in this instance, because the two sides coming away from the 45 degree point are NOT equal in length in a HST and they need to be equal in Givio's design.
I don't know about brilliant, but I was born in England and came to Scotland in 1972, so regard myself as a naturalised scot by now lol.
SIODACH is a Gaelic word, pronounced (as close as I can get lol) 'shuh-da-cchh', where the cchh is soft at the back of your throat as in 'loch' .
It means 'silky', particularly as a description of hair, and dates back to the time when I bred Persian cats. Siodach was/is my cattery name (and it will remain mine until 50 years after my death, he he). The word has the great advantage that if I want to sign up for something, that name has never been already taken lol.
Jan in VA
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