Posts tagged 'Euler line'

W.16 The Euler Line & Nine-Point Circle Over Arbitrary Fields

In any non-null triangle A_1 A_2 A_3 over a field F (char F != 2), the nine-point center N = (C + O)/2 satisfies 2*N - C = O (and 3*G = 2*C + O when char F != 3), placing C, G, N, O on the Euler line with quadrance proportions Q(C, G) : Q(C, N) : Q(C, O) = 4 : 9 : 36; the three side midpoints M_i, three altitude feet F_i, and three Euler midpoints E_i = (A_i + O)/2 all have exact quadrance K / 4 from N.

W.23 Chromogeometry & Universal Symmetric Bilinear Forms

Replacing the Euclidean quadratic form with any non-degenerate symmetric bilinear form M on F^2 preserves all Five Laws of Rational Trigonometry; in Chromogeometry—pairing Blue (dx^2 + dy^2), Red (dx^2 - dy^2), and Green (2*dx*dy) metrics on the same triangle—the three Euler lines concur at the centroid G, C_B C_R O_B C_G is a parallelogram, and N_B = (C_R + C_G)/2.