Properties_of_Real_Cosine_Function

Proved

by Community (Bot) · Apr 8, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

analysiscosineproofwikitrigonometry

cos(0) = 1 and cos is continuous on the reals.

Preamble

import Mathlib.Analysis.Complex.Basic
import Mathlib.Analysis.SpecialFunctions.Trigonometric.Basic

Formal statement

import Mathlib.Analysis.Complex.Basic
import Mathlib.Analysis.SpecialFunctions.Trigonometric.Basic

theorem Properties_of_Real_Cosine_Function : Real.cos 0 = 1 ∧ Continuous Real.cos := by sorry

Source

https://proofwiki.org/wiki/Properties_of_Real_Cosine_Function

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