$z_1$

$z_2$

$z_3$

$\gamma_{2}$

Im

Re

$\gamma_{t_1}$

$\gamma_{3}$

$\gamma_{1}$

Z_1 = (1, 1)
Z_2 = (6, 2)
Z_3: (3, 6)
v_{1,n} = Vector(Z_1, Z_2)
t = 0.46 (slider from 0 to 1, step 0.02)
Z1 = NaN
Z2 = NaN
Z2K: ((1 - t) * Z_1) + (t * Z_2)
Z3K: ((1 - t) * Z_1) + (t * Z_3)
gamma_t = Vector(Z3K, Z2K)
Z = Point(gamma_t)
d1, z_3, z_1, z_2 = Polygon(Z_1, Z_2, Z_3)
v_{3,n} = Vector(Z_1, Z_3)
v_{2,n} = Vector(Z_3, Z_2)