26 lines
679 B
Plaintext
26 lines
679 B
Plaintext
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import Mathlib.Data.Real.Basic
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/-! # Common.Real.Trigonometry
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Additional theorems and definitions useful in the context of trigonometry. Most
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of these will likely be deleted once the corresponding functions in `Mathlib`
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are ported to Lean 4.
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-/
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namespace Real
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/--
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The standard `π` variable with value `3.14159...`.
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-/
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axiom pi : ℝ
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/--
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The undirected angle at `p₂` between the line segments to `p₁` and `p₃`. If
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either of those points equals `p₂`, this is `π / 2`.
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-/
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axiom angle (p₁ p₂ p₃ : ℝ × ℝ) : ℝ
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noncomputable def euclideanAngle (p₁ p₂ p₃ : ℝ × ℝ) :=
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if p₁ = p₂ ∨ p₂ = p₃ then pi / 2 else angle p₁ p₂ p₃
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end Real
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