English
The distance between z and its conjugate is the same as between z and its conjugate (commutativity): dist(z, \overline{z}) = dist(\overline{z}, z) = 2|Im z|.
Русский
Расстояние между z и сопряженным равно расстоянию между сопряженным и z: dist(z, \overline{z}) = dist(\overline{z}, z) = 2|Im z|.
LaTeX
$$$\\\\operatorname{dist}(z, \\overline{z}) = 2 \\, |\\\\operatorname{Im} z|$$$
Lean4
theorem dist_self_conj (z : ℂ) : dist z (conj z) = 2 * |z.im| := by rw [dist_comm, dist_conj_self]