case h.e'_2.h.e'_1
z : ℂ
h :
  ((∀ (k : ℤ), ↑z.re ≠ (2 * ↑k + 1) * ↑π / 2) ∧ ∀ (l : ℤ), ↑z.im * I ≠ (2 * ↑l + 1) * ↑π / 2) ∨
    (∃ k, ↑z.re = (2 * ↑k + 1) * ↑π / 2) ∧ ∃ l, ↑z.im * I = (2 * ↑l + 1) * ↑π / 2
⊢ z = ↑z.re + ↑z.im * I
z : ℂ
h :
  ((∀ (k : ℤ), ↑z.re ≠ (2 * ↑k + 1) * ↑π / 2) ∧ ∀ (l : ℤ), ↑z.im * I ≠ (2 * ↑l + 1) * ↑π / 2) ∨
    (∃ k, ↑z.re = (2 * ↑k + 1) * ↑π / 2) ∧ ∃ l, ↑z.im * I = (2 * ↑l + 1) * ↑π / 2
⊢ tan z = (tan ↑z.re + tanh ↑z.im * I) / (1 - tan ↑z.re * tanh ↑z.im * I)
convert tan_add_mul_I h
no goals
case h.e'_2.h.e'_1
z : ℂ
h :
  ((∀ (k : ℤ), ↑z.re ≠ (2 * ↑k + 1) * ↑π / 2) ∧ ∀ (l : ℤ), ↑z.im * I ≠ (2 * ↑l + 1) * ↑π / 2) ∨
    (∃ k, ↑z.re = (2 * ↑k + 1) * ↑π / 2) ∧ ∃ l, ↑z.im * I = (2 * ↑l + 1) * ↑π / 2
⊢ z = ↑z.re + ↑z.im * I
exact (re_add_im z).symm