t0 = X2-X1 A = t0^2 B = X1*A C = X2*A t1 = Y2-Y1 D = t1^2 t2 = D-B X3 = t2-C t3 = Y2-Y1 t4 = B-X3 t5 = C-B t6 = Y1*t5 t7 = t3*t4 Y3 = t7-t6 t8 = X2-X1 Z3 = Z1*t8