选择题
2001 AMC 8 Problem 23: Noncongruent Triangles from Midpoints
Points R, S and T are vertices of an equilateral triangle, and points X, Y and Z are midpoints of its sides. How many noncongruent triangles can be drawn using any three of these six points as vertices?
A.
1
B.
2
C.
3
D.
4
E.
20