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CEMC Gauss (Grade 7), 2003

Combinatorics Difficulty 3.0 AMC 10/12 Find the answer Canada

Six points $A$ , $B$ , $C$ , $D$ , $E$ , and $F$ are placed on a square grid, as shown. How many triangles that are not right-angled can be drawn by using 3 of these 6 points as vertices?

(A) $2$ (B) $1$ (C) $6$ (D) $0$ (E) $4$

Figure for this problem

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