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		   2 items are filed under this topic. 
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    Can you construct a regular 21-gon? | 
  2016-03-08 | 
   
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  From Peter: hi, i know that if i use a compass to draw a circle, i can use the same setting to mark 6 intervals along the circle circumference, how would i go about marking out 21 equally spaced points around the circumference?
  
if there an online calculator i can us, or some other interesting trick?
  
tia
  
peter Answered by Robert Dawson. | 
   
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    3 equidistant points on a circle | 
  2010-06-21 | 
   
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  From Brian: We have to line up 3 pins on a lifting bridle to be 120 degrees apart from each other to connect into a lifting assembly. 
I know pi*d. I know straight lines connecting these points to each other will result in an equilateral triangle.
How does one find these points without using a protractor? There must be a formula (formulae) to work this out mathematically. 
r = 10.5 inches 
pi*d = 65.9736 
3 segments( arcs) = 21.9912 which is the distance along the circumference that the points are from each other. Answered by Penny Nom. | 
   
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