Thứ Sáu, 12 tháng 9, 2014

22-X(15) or X(16) and three antipode lie on a circle

Let ABC be a triangle. Construct three equilateral triangle on the side: \triangle ABC_1, \triangle BCA_1, \triangle CAB_1 ( either all outward, or all inward).

Construct circle through A, and through midpoints of AC_1,AB_1, center of circle is C_A
Construct circle through B, and through midpoints of BC_1,BA_1, center of circle is C_B
Construct circle through C, and through midpoints of AC_1,AB_1, center of circle is C_C.

Prove that:
-A' is antipode of A with (C_A)
B' is antipode of B with (C_B)
C' is antipode of C with (C_C)
Four points: X_{16} or X_{15} and A',B',C' lie on a circle

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