theorem
proved
term proof
cosh_initials
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formal statement (Lean)
407theorem cosh_initials : Real.cosh 0 = 1 ∧ deriv (fun x => Real.cosh x) 0 = 0 := by
proof body
Term-mode proof.
408 constructor
409 · simp [Real.cosh_zero]
410 · have h := Real.deriv_cosh
411 simp only [h, Real.sinh_zero]
412
413/-- **Theorem (ODE Cosh Uniqueness)**: The unique solution to H'' = H with H(0) = 1, H'(0) = 0 is cosh. -/