  Math Central - mathcentral.uregina.ca  Quandaries & Queries    Q & Q    Topic: around a circle   start over

2 items are filed under this topic.    Page1/1            Can you construct a regular 21-gon? 2016-03-08 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 peterAnswered by Robert Dawson.     3 equidistant points on a circle 2010-06-21 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.      Page1/1    Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.    about math central :: site map :: links :: notre site français