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MathNet 2000 — Math Olympiad Vault Question 36

Math Olympiad Vault · MathNet 2000 — Math Olympiad Vault

Question 36

Equilateral triangles $A B C_{1}$, $B C A_{1}$, $C A B_{1}$ are constructed outwards on the sides of a triangle $A B C$. Prove:

a. The centers of these three triangles form another equilateral triangle.

b. Segments $A A_{1}$, $B B_{1}$, $C C_{1}$ are concurrent.

c. Segments $A A_{1}$, $B B_{1}$, $C C_{1}$ have equal lengths.