5G-s-P6

Let Ai, i = 1, 2, . . . , 5, be any five points.

Taking subscripts modulo 5, we denote, for i = 1, 2, . . . , 5,

the intersection of the lines AiAi+1 and Ai+2Ai+3 by Bi+3,

the second intersection of two circles (AiAi+1Bi+2) and (Ai+1Ai+2Bi+3) by Ci+1,

the center of circle (AiAi+1Bi+2) by Ki+2, and the center of circle (Ci+1Bi+2Bi+3) by Li.

Then five lines KiLi, for i = 1, 2, . . . , 5, are concurrent at a point 5G-s-P6.

This theorem was found by Tran Quang Hung at [70], Theorem 4.

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