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CEMC Gauss (Grade 8), 2010

Combinatorics Difficulty 1.0 Junior Find the answer Canada

Distinct points are placed on a circle. Each pair of points is joined with a line segment. An example with $4$ points and $6$ line segments is shown. If $8$ distinct points are placed on a circle, how many line segments would there be?

(A) $27$ (B) $36$ (C) $21$ (D) $56$ (E) $28$

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