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Perpendiculars Picking Probability (Posted on 2005-11-24) Difficulty: 3 of 5
You choose a random point, uniformly, within an equilateral triangle.

What's the average distance to the three sides?

  Submitted by Old Original Oskar!    
Rating: 3.8000 (5 votes)
Solution: (Hide)
Pick any P. Draw lines from P to each vertex. These lines divide the equilateral triangle into three triangles. Each of these triangles has as its base one side of the equilateral triangle and as its height the perpendicular distance from P to that side. The sum of the areas of these triangles equals the area of the original triangle. So, the sum of the three distances from P to the sides, is the same as the height of the original triangle. Thus, the average distance to the sides is √3/6 times the side of the triangle.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Some ThoughtsQuick and dirty solution; not a proofLarry2020-04-23 06:48:48
AnswerK Sengupta2008-10-03 02:42:58
Any triangleFederico Kereki2005-11-24 11:00:29
SolutionSolutionBractals2005-11-24 10:41:53
SolutionOld problemgoFish2005-11-24 10:06:11
SolutionSolutionKen Haley2005-11-24 09:44:07
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