Problem:
Points and are vertices of an equilateral triangle, and points and are midpoints of its sides. How many noncongruent triangles can be drawn using any three of these six points as vertices?
.jpg)
Answer Choices:
A.
B.
C.
D.
E.
Solution:
There are four noncongruent triangles.
The seventeen possible triangles may be divided into four congruence classes:
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions