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A pool rack filled with balls (Posted on 2004-09-17) Difficulty: 3 of 5
A pool rack is an equilateral triangle, filled with 15 equal-sized balls. Seen from above, we'd see a triangle, with 15 circles within.

Imagine we used smaller and smaller balls. The more the balls, more area of the triangle would be covered.

In the limit, with infinite balls, would all of the triangle be covered?

See The Solution Submitted by Federico Kereki    
Rating: 3.3636 (11 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Solution | Comment 19 of 25 |

Take a "triangular" number of balls n(n+1)/2 of unit radius. These balls cover an area of pi*n(n+1)/2. The area of the equilateral triangle bounding these balls is √3*(n+√3-1)^2. The ratio of the area covered by the balls to the area of triangle is

{pi√3/6}*{n(n+1)/(n+√3-1)^2}. As n goes to infinity, this ratio approaches pi√3/6 ~= 0.9069.

Would all of the triangle be covered? No.

  Posted by Bractals on 2004-09-21 17:39:54
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