The orthic axis of the excentral triangle, which is central line L_1 and therefore has trilinear equation α + β + γ = 0. It is the trilinear polar of the incenter. The line passes through Kimberling centers X_i for i = 44, 513, 649, 650, 652, 654, 656, 657, 659, 661, 672, 770, 798, 822, 851, 896, 899, 910, 1155, 1491, 1575, 1635, 1755, 2173, 2182, 2183, 2225, 2227, 2228, 2229, 2230, 2231, 2232, 2233, 2234, 2235, 2236, 2237, 2238, 2239, 2240, 2243, 2244, 2245, 2246, 2247, 2252, 2253, 2254, 2265, 2272, 2290, 2312, 2313, 2314, 2315, 2348, 2483, 2484, 2503, 2511, 2515, 2516, 2522, 2526, 2578, 2579, 2590, 2591, 2600, 2610, 2624, 2630, 2631, 2635, 2637, 2641, 2642, 3000, and 3013.

central line | coaxal system | orthic axis