P. 265 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 26401-26500   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	pserdv2 26401*	The derivative of a power series on its region of convergence. (Contributed by Mario Carneiro, 31-Mar-2015.)
⊢ 𝐺 = (𝑥 ∈ ℂ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐴‘𝑛) · (𝑥↑𝑛))))    &   ⊢ 𝐹 = (𝑦 ∈ 𝑆 ↦ Σ𝑗 ∈ ℕ0 ((𝐺‘𝑦)‘𝑗))    &   ⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ 𝑅 = sup({𝑟 ∈ ℝ ∣ seq0( + , (𝐺‘𝑟)) ∈ dom ⇝ }, ℝ*, < )    &   ⊢ 𝑆 = (◡abs “ (0[,)𝑅))    &   ⊢ 𝑀 = if(𝑅 ∈ ℝ, (((abs‘𝑎) + 𝑅) / 2), ((abs‘𝑎) + 1))    &   ⊢ 𝐵 = (0(ball‘(abs ∘ − ))(((abs‘𝑎) + 𝑀) / 2))    ⇒   ⊢ (𝜑 → (ℂ D 𝐹) = (𝑦 ∈ 𝑆 ↦ Σ𝑘 ∈ ℕ ((𝑘 · (𝐴‘𝑘)) · (𝑦↑(𝑘 − 1)))))
Theorem	abelthlem1 26402*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 1-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    ⇒   ⊢ (𝜑 → 1 ≤ sup({𝑟 ∈ ℝ ∣ seq0( + , ((𝑧 ∈ ℂ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐴‘𝑛) · (𝑧↑𝑛))))‘𝑟)) ∈ dom ⇝ }, ℝ*, < ))
Theorem	abelthlem2 26403*	Lemma for abelth 26412. The peculiar region 𝑆, known as a Stolz angle , is a teardrop-shaped subset of the closed unit ball containing 1. Indeed, except for 1 itself, the rest of the Stolz angle is enclosed in the open unit ball. (Contributed by Mario Carneiro, 31-Mar-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    ⇒   ⊢ (𝜑 → (1 ∈ 𝑆 ∧ (𝑆 ∖ {1}) ⊆ (0(ball‘(abs ∘ − ))1)))
Theorem	abelthlem3 26404*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 31-Mar-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    ⇒   ⊢ ((𝜑 ∧ 𝑋 ∈ 𝑆) → seq0( + , (𝑛 ∈ ℕ0 ↦ ((𝐴‘𝑛) · (𝑋↑𝑛)))) ∈ dom ⇝ )
Theorem	abelthlem4 26405*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 31-Mar-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    ⇒   ⊢ (𝜑 → 𝐹:𝑆⟶ℂ)
Theorem	abelthlem5 26406*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 1-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    &   ⊢ (𝜑 → seq0( + , 𝐴) ⇝ 0)    ⇒   ⊢ ((𝜑 ∧ 𝑋 ∈ (0(ball‘(abs ∘ − ))1)) → seq0( + , (𝑘 ∈ ℕ0 ↦ ((seq0( + , 𝐴)‘𝑘) · (𝑋↑𝑘)))) ∈ dom ⇝ )
Theorem	abelthlem6 26407*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 2-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    &   ⊢ (𝜑 → seq0( + , 𝐴) ⇝ 0)    &   ⊢ (𝜑 → 𝑋 ∈ (𝑆 ∖ {1}))    ⇒   ⊢ (𝜑 → (𝐹‘𝑋) = ((1 − 𝑋) · Σ𝑛 ∈ ℕ0 ((seq0( + , 𝐴)‘𝑛) · (𝑋↑𝑛))))
Theorem	abelthlem7a 26408*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 8-May-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    &   ⊢ (𝜑 → seq0( + , 𝐴) ⇝ 0)    &   ⊢ (𝜑 → 𝑋 ∈ (𝑆 ∖ {1}))    ⇒   ⊢ (𝜑 → (𝑋 ∈ ℂ ∧ (abs‘(1 − 𝑋)) ≤ (𝑀 · (1 − (abs‘𝑋)))))
Theorem	abelthlem7 26409*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 2-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    &   ⊢ (𝜑 → seq0( + , 𝐴) ⇝ 0)    &   ⊢ (𝜑 → 𝑋 ∈ (𝑆 ∖ {1}))    &   ⊢ (𝜑 → 𝑅 ∈ ℝ+)    &   ⊢ (𝜑 → 𝑁 ∈ ℕ0)    &   ⊢ (𝜑 → ∀𝑘 ∈ (ℤ≥‘𝑁)(abs‘(seq0( + , 𝐴)‘𝑘)) < 𝑅)    &   ⊢ (𝜑 → (abs‘(1 − 𝑋)) < (𝑅 / (Σ𝑛 ∈ (0...(𝑁 − 1))(abs‘(seq0( + , 𝐴)‘𝑛)) + 1)))    ⇒   ⊢ (𝜑 → (abs‘(𝐹‘𝑋)) < ((𝑀 + 1) · 𝑅))
Theorem	abelthlem8 26410*	Lemma for abelth 26412. (Contributed by Mario Carneiro, 2-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    &   ⊢ (𝜑 → seq0( + , 𝐴) ⇝ 0)    ⇒   ⊢ ((𝜑 ∧ 𝑅 ∈ ℝ+) → ∃𝑤 ∈ ℝ+ ∀𝑦 ∈ 𝑆 ((abs‘(1 − 𝑦)) < 𝑤 → (abs‘((𝐹‘1) − (𝐹‘𝑦))) < 𝑅))
Theorem	abelthlem9 26411*	Lemma for abelth 26412. By adjusting the constant term, we can assume that the entire series converges to 0. (Contributed by Mario Carneiro, 1-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    ⇒   ⊢ ((𝜑 ∧ 𝑅 ∈ ℝ+) → ∃𝑤 ∈ ℝ+ ∀𝑦 ∈ 𝑆 ((abs‘(1 − 𝑦)) < 𝑤 → (abs‘((𝐹‘1) − (𝐹‘𝑦))) < 𝑅))
Theorem	abelth 26412*	Abel's theorem. If the power series Σ𝑛 ∈ ℕ0𝐴(𝑛)(𝑥↑𝑛) is convergent at 1, then it is equal to the limit from "below", along a Stolz angle 𝑆 (note that the 𝑀 = 1 case of a Stolz angle is the real line [0, 1]). (Continuity on 𝑆 ∖ {1} follows more generally from psercn 26397.) (Contributed by Mario Carneiro, 2-Apr-2015.) (Revised by Mario Carneiro, 8-Sep-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ (𝜑 → 𝑀 ∈ ℝ)    &   ⊢ (𝜑 → 0 ≤ 𝑀)    &   ⊢ 𝑆 = {𝑧 ∈ ℂ ∣ (abs‘(1 − 𝑧)) ≤ (𝑀 · (1 − (abs‘𝑧)))}    &   ⊢ 𝐹 = (𝑥 ∈ 𝑆 ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    ⇒   ⊢ (𝜑 → 𝐹 ∈ (𝑆–cn→ℂ))
Theorem	abelth2 26413*	Abel's theorem, restricted to the [0, 1] interval. (Contributed by Mario Carneiro, 2-Apr-2015.)
⊢ (𝜑 → 𝐴:ℕ0⟶ℂ)    &   ⊢ (𝜑 → seq0( + , 𝐴) ∈ dom ⇝ )    &   ⊢ 𝐹 = (𝑥 ∈ (0[,]1) ↦ Σ𝑛 ∈ ℕ0 ((𝐴‘𝑛) · (𝑥↑𝑛)))    ⇒   ⊢ (𝜑 → 𝐹 ∈ ((0[,]1)–cn→ℂ))
14.3  Basic trigonometry
14.3.1  The exponential, sine, and cosine functions (cont.)
Theorem	efcn 26414	The exponential function is continuous. (Contributed by Paul Chapman, 15-Sep-2007.) (Revised by Mario Carneiro, 20-Jun-2015.)
⊢ exp ∈ (ℂ–cn→ℂ)
Theorem	sincn 26415	Sine is continuous. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Mario Carneiro, 3-Sep-2014.)
⊢ sin ∈ (ℂ–cn→ℂ)
Theorem	coscn 26416	Cosine is continuous. (Contributed by Paul Chapman, 28-Nov-2007.) (Revised by Mario Carneiro, 3-Sep-2014.)
⊢ cos ∈ (ℂ–cn→ℂ)
Theorem	reeff1olem 26417*	Lemma for reeff1o 26418. (Contributed by Paul Chapman, 18-Oct-2007.) (Revised by Mario Carneiro, 30-Apr-2014.)
⊢ ((𝑈 ∈ ℝ ∧ 1 < 𝑈) → ∃𝑥 ∈ ℝ (exp‘𝑥) = 𝑈)
Theorem	reeff1o 26418	The real exponential function is one-to-one onto. (Contributed by Paul Chapman, 18-Oct-2007.) (Revised by Mario Carneiro, 10-Nov-2013.)
⊢ (exp ↾ ℝ):ℝ–1-1-onto→ℝ+
Theorem	reefiso 26419	The exponential function on the reals determines an isomorphism from reals onto positive reals. (Contributed by Steve Rodriguez, 25-Nov-2007.) (Revised by Mario Carneiro, 11-Mar-2014.)
⊢ (exp ↾ ℝ) Isom < , < (ℝ, ℝ+)
Theorem	efcvx 26420	The exponential function on the reals is a strictly convex function. (Contributed by Mario Carneiro, 20-Jun-2015.)
⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐴 < 𝐵) ∧ 𝑇 ∈ (0(,)1)) → (exp‘((𝑇 · 𝐴) + ((1 − 𝑇) · 𝐵))) < ((𝑇 · (exp‘𝐴)) + ((1 − 𝑇) · (exp‘𝐵))))
Theorem	reefgim 26421	The exponential function is a group isomorphism from the group of reals under addition to the group of positive reals under multiplication. (Contributed by Mario Carneiro, 21-Jun-2015.) (Revised by Thierry Arnoux, 30-Jun-2019.)
⊢ 𝑃 = ((mulGrp‘ℂfld) ↾s ℝ+)    ⇒   ⊢ (exp ↾ ℝ) ∈ (ℝfld GrpIso 𝑃)
14.3.2  Properties of pi = 3.14159...
Theorem	pilem1 26422	Lemma for pire 26427, pigt2lt4 26425 and sinpi 26426. (Contributed by Mario Carneiro, 9-May-2014.)
⊢ (𝐴 ∈ (ℝ+ ∩ (◡sin “ {0})) ↔ (𝐴 ∈ ℝ+ ∧ (sin‘𝐴) = 0))
Theorem	pilem2 26423	Lemma for pire 26427, pigt2lt4 26425 and sinpi 26426. (Contributed by Mario Carneiro, 12-Jun-2014.) (Revised by AV, 14-Sep-2020.)
⊢ (𝜑 → 𝐴 ∈ (2(,)4))    &   ⊢ (𝜑 → 𝐵 ∈ ℝ+)    &   ⊢ (𝜑 → (sin‘𝐴) = 0)    &   ⊢ (𝜑 → (sin‘𝐵) = 0)    ⇒   ⊢ (𝜑 → ((π + 𝐴) / 2) ≤ 𝐵)
Theorem	pilem3 26424	Lemma for pire 26427, pigt2lt4 26425 and sinpi 26426. Existence part. (Contributed by Paul Chapman, 23-Jan-2008.) (Proof shortened by Mario Carneiro, 18-Jun-2014.) (Revised by AV, 14-Sep-2020.) (Proof shortened by BJ, 30-Jun-2022.)
⊢ (π ∈ (2(,)4) ∧ (sin‘π) = 0)
Theorem	pigt2lt4 26425	π is between 2 and 4. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 9-May-2014.)
⊢ (2 < π ∧ π < 4)
Theorem	sinpi 26426	The sine of π is 0. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (sin‘π) = 0
Theorem	pire 26427	π is a real number. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ π ∈ ℝ
Theorem	picn 26428	π is a complex number. (Contributed by David A. Wheeler, 6-Dec-2018.)
⊢ π ∈ ℂ
Theorem	pipos 26429	π is positive. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 9-May-2014.)
⊢ 0 < π
Theorem	pine0 26430	π is nonzero. (Contributed by SN, 25-Apr-2025.)
⊢ π ≠ 0
Theorem	pirp 26431	π is a positive real. (Contributed by Glauco Siliprandi, 11-Dec-2019.)
⊢ π ∈ ℝ+
Theorem	negpicn 26432	-π is a real number. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ -π ∈ ℂ
Theorem	sinhalfpilem 26433	Lemma for sinhalfpi 26438 and coshalfpi 26439. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ ((sin‘(π / 2)) = 1 ∧ (cos‘(π / 2)) = 0)
Theorem	halfpire 26434	π / 2 is real. (Contributed by David Moews, 28-Feb-2017.)
⊢ (π / 2) ∈ ℝ
Theorem	neghalfpire 26435	-π / 2 is real. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ -(π / 2) ∈ ℝ
Theorem	neghalfpirx 26436	-π / 2 is an extended real. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ -(π / 2) ∈ ℝ*
Theorem	pidiv2halves 26437	Adding π / 2 to itself gives π. See 2halves 12364. (Contributed by David A. Wheeler, 8-Dec-2018.)
⊢ ((π / 2) + (π / 2)) = π
Theorem	sinhalfpi 26438	The sine of π / 2 is 1. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (sin‘(π / 2)) = 1
Theorem	coshalfpi 26439	The cosine of π / 2 is 0. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (cos‘(π / 2)) = 0
Theorem	cosneghalfpi 26440	The cosine of -π / 2 is zero. (Contributed by David Moews, 28-Feb-2017.)
⊢ (cos‘-(π / 2)) = 0
Theorem	efhalfpi 26441	The exponential of iπ / 2 is i. (Contributed by Mario Carneiro, 9-May-2014.)
⊢ (exp‘(i · (π / 2))) = i
Theorem	cospi 26442	The cosine of π is -1. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (cos‘π) = -1
Theorem	efipi 26443	The exponential of i · π is -1. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (exp‘(i · π)) = -1
Theorem	eulerid 26444	Euler's identity. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 9-May-2014.)
⊢ ((exp‘(i · π)) + 1) = 0
Theorem	sin2pi 26445	The sine of 2π is 0. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (sin‘(2 · π)) = 0
Theorem	cos2pi 26446	The cosine of 2π is 1. (Contributed by Paul Chapman, 23-Jan-2008.)
⊢ (cos‘(2 · π)) = 1
Theorem	ef2pi 26447	The exponential of 2πi is 1. (Contributed by Mario Carneiro, 9-May-2014.)
⊢ (exp‘(i · (2 · π))) = 1
Theorem	ef2kpi 26448	If 𝐾 is an integer, then the exponential of 2𝐾πi is 1. (Contributed by Mario Carneiro, 9-May-2014.)
⊢ (𝐾 ∈ ℤ → (exp‘((i · (2 · π)) · 𝐾)) = 1)
Theorem	efper 26449	The exponential function is periodic. (Contributed by Paul Chapman, 21-Apr-2008.) (Proof shortened by Mario Carneiro, 10-May-2014.)
⊢ ((𝐴 ∈ ℂ ∧ 𝐾 ∈ ℤ) → (exp‘(𝐴 + ((i · (2 · π)) · 𝐾))) = (exp‘𝐴))
Theorem	sinperlem 26450	Lemma for sinper 26451 and cosper 26452. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (𝐴 ∈ ℂ → (𝐹‘𝐴) = (((exp‘(i · 𝐴))𝑂(exp‘(-i · 𝐴))) / 𝐷))    &   ⊢ ((𝐴 + (𝐾 · (2 · π))) ∈ ℂ → (𝐹‘(𝐴 + (𝐾 · (2 · π)))) = (((exp‘(i · (𝐴 + (𝐾 · (2 · π)))))𝑂(exp‘(-i · (𝐴 + (𝐾 · (2 · π)))))) / 𝐷))    ⇒   ⊢ ((𝐴 ∈ ℂ ∧ 𝐾 ∈ ℤ) → (𝐹‘(𝐴 + (𝐾 · (2 · π)))) = (𝐹‘𝐴))
Theorem	sinper 26451	The sine function is periodic. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ ((𝐴 ∈ ℂ ∧ 𝐾 ∈ ℤ) → (sin‘(𝐴 + (𝐾 · (2 · π)))) = (sin‘𝐴))
Theorem	cosper 26452	The cosine function is periodic. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ ((𝐴 ∈ ℂ ∧ 𝐾 ∈ ℤ) → (cos‘(𝐴 + (𝐾 · (2 · π)))) = (cos‘𝐴))
Theorem	sin2kpi 26453	If 𝐾 is an integer, then the sine of 2𝐾π is 0. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (𝐾 ∈ ℤ → (sin‘(𝐾 · (2 · π))) = 0)
Theorem	cos2kpi 26454	If 𝐾 is an integer, then the cosine of 2𝐾π is 1. (Contributed by Paul Chapman, 23-Jan-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (𝐾 ∈ ℤ → (cos‘(𝐾 · (2 · π))) = 1)
Theorem	sin2pim 26455	Sine of a number subtracted from 2 · π. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ ℂ → (sin‘((2 · π) − 𝐴)) = -(sin‘𝐴))
Theorem	cos2pim 26456	Cosine of a number subtracted from 2 · π. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ ℂ → (cos‘((2 · π) − 𝐴)) = (cos‘𝐴))
Theorem	sinmpi 26457	Sine of a number less π. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ ℂ → (sin‘(𝐴 − π)) = -(sin‘𝐴))
Theorem	cosmpi 26458	Cosine of a number less π. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ ℂ → (cos‘(𝐴 − π)) = -(cos‘𝐴))
Theorem	sinppi 26459	Sine of a number plus π. (Contributed by NM, 10-Aug-2008.)
⊢ (𝐴 ∈ ℂ → (sin‘(𝐴 + π)) = -(sin‘𝐴))
Theorem	cosppi 26460	Cosine of a number plus π. (Contributed by NM, 18-Aug-2008.)
⊢ (𝐴 ∈ ℂ → (cos‘(𝐴 + π)) = -(cos‘𝐴))
Theorem	efimpi 26461	The exponential function at i times a real number less π. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ ℂ → (exp‘(i · (𝐴 − π))) = -(exp‘(i · 𝐴)))
Theorem	sinhalfpip 26462	The sine of π / 2 plus a number. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ℂ → (sin‘((π / 2) + 𝐴)) = (cos‘𝐴))
Theorem	sinhalfpim 26463	The sine of π / 2 minus a number. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ℂ → (sin‘((π / 2) − 𝐴)) = (cos‘𝐴))
Theorem	coshalfpip 26464	The cosine of π / 2 plus a number. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ℂ → (cos‘((π / 2) + 𝐴)) = -(sin‘𝐴))
Theorem	coshalfpim 26465	The cosine of π / 2 minus a number. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ℂ → (cos‘((π / 2) − 𝐴)) = (sin‘𝐴))
Theorem	ptolemy 26466	Ptolemy's Theorem. This theorem is named after the Greek astronomer and mathematician Ptolemy (Claudius Ptolemaeus). This particular version is expressed using the sine function. It is proved by expanding all the multiplication of sines to a product of cosines of differences using sinmul 16102, then using algebraic simplification to show that both sides are equal. This formalization is based on the proof in "Trigonometry" by Gelfand and Saul. This is Metamath 100 proof #95. (Contributed by David A. Wheeler, 31-May-2015.)
⊢ (((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) ∧ (𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ) ∧ ((𝐴 + 𝐵) + (𝐶 + 𝐷)) = π) → (((sin‘𝐴) · (sin‘𝐵)) + ((sin‘𝐶) · (sin‘𝐷))) = ((sin‘(𝐵 + 𝐶)) · (sin‘(𝐴 + 𝐶))))
Theorem	sincosq1lem 26467	Lemma for sincosq1sgn 26468. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ ((𝐴 ∈ ℝ ∧ 0 < 𝐴 ∧ 𝐴 < (π / 2)) → 0 < (sin‘𝐴))
Theorem	sincosq1sgn 26468	The signs of the sine and cosine functions in the first quadrant. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ (0(,)(π / 2)) → (0 < (sin‘𝐴) ∧ 0 < (cos‘𝐴)))
Theorem	sincosq2sgn 26469	The signs of the sine and cosine functions in the second quadrant. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ((π / 2)(,)π) → (0 < (sin‘𝐴) ∧ (cos‘𝐴) < 0))
Theorem	sincosq3sgn 26470	The signs of the sine and cosine functions in the third quadrant. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ (π(,)(3 · (π / 2))) → ((sin‘𝐴) < 0 ∧ (cos‘𝐴) < 0))
Theorem	sincosq4sgn 26471	The signs of the sine and cosine functions in the fourth quadrant. (Contributed by Paul Chapman, 24-Jan-2008.)
⊢ (𝐴 ∈ ((3 · (π / 2))(,)(2 · π)) → ((sin‘𝐴) < 0 ∧ 0 < (cos‘𝐴)))
Theorem	coseq00topi 26472	Location of the zeroes of cosine in (0[,]π). (Contributed by David Moews, 28-Feb-2017.)
⊢ (𝐴 ∈ (0[,]π) → ((cos‘𝐴) = 0 ↔ 𝐴 = (π / 2)))
Theorem	coseq0negpitopi 26473	Location of the zeroes of cosine in (-π(,]π). (Contributed by David Moews, 28-Feb-2017.)
⊢ (𝐴 ∈ (-π(,]π) → ((cos‘𝐴) = 0 ↔ 𝐴 ∈ {(π / 2), -(π / 2)}))
Theorem	tanrpcl 26474	Positive real closure of the tangent function. (Contributed by Mario Carneiro, 29-Jul-2014.)
⊢ (𝐴 ∈ (0(,)(π / 2)) → (tan‘𝐴) ∈ ℝ+)
Theorem	tangtx 26475	The tangent function is greater than its argument on positive reals in its principal domain. (Contributed by Mario Carneiro, 29-Jul-2014.)
⊢ (𝐴 ∈ (0(,)(π / 2)) → 𝐴 < (tan‘𝐴))
Theorem	tanabsge 26476	The tangent function is greater than or equal to its argument in absolute value. (Contributed by Mario Carneiro, 25-Feb-2015.)
⊢ (𝐴 ∈ (-(π / 2)(,)(π / 2)) → (abs‘𝐴) ≤ (abs‘(tan‘𝐴)))
Theorem	sinq12gt0 26477	The sine of a number strictly between 0 and π is positive. (Contributed by Paul Chapman, 15-Mar-2008.)
⊢ (𝐴 ∈ (0(,)π) → 0 < (sin‘𝐴))
Theorem	sinq12ge0 26478	The sine of a number between 0 and π is nonnegative. (Contributed by Mario Carneiro, 13-May-2014.)
⊢ (𝐴 ∈ (0[,]π) → 0 ≤ (sin‘𝐴))
Theorem	sinq34lt0t 26479	The sine of a number strictly between π and 2 · π is negative. (Contributed by NM, 17-Aug-2008.)
⊢ (𝐴 ∈ (π(,)(2 · π)) → (sin‘𝐴) < 0)
Theorem	cosq14gt0 26480	The cosine of a number strictly between -π / 2 and π / 2 is positive. (Contributed by Mario Carneiro, 25-Feb-2015.)
⊢ (𝐴 ∈ (-(π / 2)(,)(π / 2)) → 0 < (cos‘𝐴))
Theorem	cosq14ge0 26481	The cosine of a number between -π / 2 and π / 2 is nonnegative. (Contributed by Mario Carneiro, 13-May-2014.)
⊢ (𝐴 ∈ (-(π / 2)[,](π / 2)) → 0 ≤ (cos‘𝐴))
Theorem	sincosq1eq 26482	Complementarity of the sine and cosine functions in the first quadrant. (Contributed by Paul Chapman, 25-Jan-2008.)
⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ (𝐴 + 𝐵) = 1) → (sin‘(𝐴 · (π / 2))) = (cos‘(𝐵 · (π / 2))))
Theorem	sincos4thpi 26483	The sine and cosine of π / 4. (Contributed by Paul Chapman, 25-Jan-2008.)
⊢ ((sin‘(π / 4)) = (1 / (√‘2)) ∧ (cos‘(π / 4)) = (1 / (√‘2)))
Theorem	tan4thpi 26484	The tangent of π / 4. (Contributed by Mario Carneiro, 5-Apr-2015.) (Proof shortened by SN, 2-Sep-2025.)
⊢ (tan‘(π / 4)) = 1
Theorem	tan4thpiOLD 26485	Obsolete version of tan4thpi 26484 as of 2-Sep-2025. (Contributed by Mario Carneiro, 5-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ (tan‘(π / 4)) = 1
Theorem	sincos6thpi 26486	The sine and cosine of π / 6. (Contributed by Paul Chapman, 25-Jan-2008.) (Revised by Wolf Lammen, 24-Sep-2020.)
⊢ ((sin‘(π / 6)) = (1 / 2) ∧ (cos‘(π / 6)) = ((√‘3) / 2))
Theorem	sincos3rdpi 26487	The sine and cosine of π / 3. (Contributed by Mario Carneiro, 21-May-2016.)
⊢ ((sin‘(π / 3)) = ((√‘3) / 2) ∧ (cos‘(π / 3)) = (1 / 2))
Theorem	pigt3 26488	π is greater than 3. (Contributed by Brendan Leahy, 21-Aug-2020.)
⊢ 3 < π
Theorem	pige3 26489	π is greater than or equal to 3. (Contributed by Mario Carneiro, 21-May-2016.)
⊢ 3 ≤ π
Theorem	pige3ALT 26490	Alternate proof of pige3 26489. This proof is based on the geometric observation that a hexagon of unit side length has perimeter 6, which is less than the unit-radius circumcircle, of perimeter 2π. We translate this to algebra by looking at the function e↑(i𝑥) as 𝑥 goes from 0 to π / 3; it moves at unit speed and travels distance 1, hence 1 ≤ π / 3. (Contributed by Mario Carneiro, 21-May-2016.) (New usage is discouraged.) (Proof modification is discouraged.)
⊢ 3 ≤ π
Theorem	abssinper 26491	The absolute value of sine has period π. (Contributed by NM, 17-Aug-2008.)
⊢ ((𝐴 ∈ ℂ ∧ 𝐾 ∈ ℤ) → (abs‘(sin‘(𝐴 + (𝐾 · π)))) = (abs‘(sin‘𝐴)))
Theorem	sinkpi 26492	The sine of an integer multiple of π is 0. (Contributed by NM, 11-Aug-2008.)
⊢ (𝐾 ∈ ℤ → (sin‘(𝐾 · π)) = 0)
Theorem	coskpi 26493	The absolute value of the cosine of an integer multiple of π is 1. (Contributed by NM, 19-Aug-2008.)
⊢ (𝐾 ∈ ℤ → (abs‘(cos‘(𝐾 · π))) = 1)
Theorem	sineq0 26494	A complex number whose sine is zero is an integer multiple of π. (Contributed by NM, 17-Aug-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (𝐴 ∈ ℂ → ((sin‘𝐴) = 0 ↔ (𝐴 / π) ∈ ℤ))
Theorem	coseq1 26495	A complex number whose cosine is one is an integer multiple of 2π. (Contributed by Mario Carneiro, 12-May-2014.)
⊢ (𝐴 ∈ ℂ → ((cos‘𝐴) = 1 ↔ (𝐴 / (2 · π)) ∈ ℤ))
Theorem	cos02pilt1 26496	Cosine is less than one between zero and 2 · π. (Contributed by Jim Kingdon, 23-Mar-2024.)
⊢ (𝐴 ∈ (0(,)(2 · π)) → (cos‘𝐴) < 1)
Theorem	cosq34lt1 26497	Cosine is less than one in the third and fourth quadrants. (Contributed by Jim Kingdon, 23-Mar-2024.)
⊢ (𝐴 ∈ (π[,)(2 · π)) → (cos‘𝐴) < 1)
Theorem	efeq1 26498	A complex number whose exponential is one is an integer multiple of 2πi. (Contributed by NM, 17-Aug-2008.) (Revised by Mario Carneiro, 10-May-2014.)
⊢ (𝐴 ∈ ℂ → ((exp‘𝐴) = 1 ↔ (𝐴 / (i · (2 · π))) ∈ ℤ))
Theorem	cosne0 26499	The cosine function has no zeroes within the vertical strip of the complex plane between real part -π / 2 and π / 2. (Contributed by Mario Carneiro, 2-Apr-2015.)
⊢ ((𝐴 ∈ ℂ ∧ (ℜ‘𝐴) ∈ (-(π / 2)(,)(π / 2))) → (cos‘𝐴) ≠ 0)
Theorem	cosordlem 26500	Lemma for cosord 26501. (Contributed by Mario Carneiro, 10-May-2014.)
⊢ (𝜑 → 𝐴 ∈ (0[,]π))    &   ⊢ (𝜑 → 𝐵 ∈ (0[,]π))    &   ⊢ (𝜑 → 𝐴 < 𝐵)    ⇒   ⊢ (𝜑 → (cos‘𝐵) < (cos‘𝐴))