SOLUTION: 15 points are placed on a circle. How many triangles is it possible to form, such that their vertices will be the given points?

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Question 1119812: 15 points are placed on a circle. How many triangles is it possible to form, such that their vertices will be the given points?
Answer by greenestamps(13209) About Me  (Show Source):
You can put this solution on YOUR website!


Any three points that are not collinear will form a triangle.

If any number of points are placed on a circle, no three of them can be collinear.

So you can form a triangle by choosing any 3 of the 15 points. The number of ways to do that is "15 choose 3"
=(15*14*13)/(3*2*1) = 455