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Mirrors > Home > MPE Home > Th. List > recos4p | Structured version Visualization version GIF version |
Description: Separate out the first four terms of the infinite series expansion of the cosine of a real number. (Contributed by Paul Chapman, 19-Jan-2008.) (Revised by Mario Carneiro, 30-Apr-2014.) |
Ref | Expression |
---|---|
efi4p.1 | ⊢ 𝐹 = (𝑛 ∈ ℕ0 ↦ (((i · 𝐴)↑𝑛) / (!‘𝑛))) |
Ref | Expression |
---|---|
recos4p | ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = ((1 − ((𝐴↑2) / 2)) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | recosval 16018 | . 2 ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = (ℜ‘(exp‘(i · 𝐴)))) | |
2 | recn 11141 | . . . . 5 ⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℂ) | |
3 | efi4p.1 | . . . . . 6 ⊢ 𝐹 = (𝑛 ∈ ℕ0 ↦ (((i · 𝐴)↑𝑛) / (!‘𝑛))) | |
4 | 3 | efi4p 16019 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (exp‘(i · 𝐴)) = (((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6)))) + Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘))) |
5 | 2, 4 | syl 17 | . . . 4 ⊢ (𝐴 ∈ ℝ → (exp‘(i · 𝐴)) = (((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6)))) + Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘))) |
6 | 5 | fveq2d 6846 | . . 3 ⊢ (𝐴 ∈ ℝ → (ℜ‘(exp‘(i · 𝐴))) = (ℜ‘(((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6)))) + Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
7 | 1re 11155 | . . . . . . 7 ⊢ 1 ∈ ℝ | |
8 | resqcl 14029 | . . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (𝐴↑2) ∈ ℝ) | |
9 | 8 | rehalfcld 12400 | . . . . . . 7 ⊢ (𝐴 ∈ ℝ → ((𝐴↑2) / 2) ∈ ℝ) |
10 | resubcl 11465 | . . . . . . 7 ⊢ ((1 ∈ ℝ ∧ ((𝐴↑2) / 2) ∈ ℝ) → (1 − ((𝐴↑2) / 2)) ∈ ℝ) | |
11 | 7, 9, 10 | sylancr 587 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → (1 − ((𝐴↑2) / 2)) ∈ ℝ) |
12 | 11 | recnd 11183 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (1 − ((𝐴↑2) / 2)) ∈ ℂ) |
13 | ax-icn 11110 | . . . . . 6 ⊢ i ∈ ℂ | |
14 | 3nn0 12431 | . . . . . . . . . 10 ⊢ 3 ∈ ℕ0 | |
15 | reexpcl 13984 | . . . . . . . . . 10 ⊢ ((𝐴 ∈ ℝ ∧ 3 ∈ ℕ0) → (𝐴↑3) ∈ ℝ) | |
16 | 14, 15 | mpan2 689 | . . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → (𝐴↑3) ∈ ℝ) |
17 | 6re 12243 | . . . . . . . . . 10 ⊢ 6 ∈ ℝ | |
18 | 6pos 12263 | . . . . . . . . . . 11 ⊢ 0 < 6 | |
19 | 17, 18 | gt0ne0ii 11691 | . . . . . . . . . 10 ⊢ 6 ≠ 0 |
20 | redivcl 11874 | . . . . . . . . . 10 ⊢ (((𝐴↑3) ∈ ℝ ∧ 6 ∈ ℝ ∧ 6 ≠ 0) → ((𝐴↑3) / 6) ∈ ℝ) | |
21 | 17, 19, 20 | mp3an23 1453 | . . . . . . . . 9 ⊢ ((𝐴↑3) ∈ ℝ → ((𝐴↑3) / 6) ∈ ℝ) |
22 | 16, 21 | syl 17 | . . . . . . . 8 ⊢ (𝐴 ∈ ℝ → ((𝐴↑3) / 6) ∈ ℝ) |
23 | resubcl 11465 | . . . . . . . 8 ⊢ ((𝐴 ∈ ℝ ∧ ((𝐴↑3) / 6) ∈ ℝ) → (𝐴 − ((𝐴↑3) / 6)) ∈ ℝ) | |
24 | 22, 23 | mpdan 685 | . . . . . . 7 ⊢ (𝐴 ∈ ℝ → (𝐴 − ((𝐴↑3) / 6)) ∈ ℝ) |
25 | 24 | recnd 11183 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → (𝐴 − ((𝐴↑3) / 6)) ∈ ℂ) |
26 | mulcl 11135 | . . . . . 6 ⊢ ((i ∈ ℂ ∧ (𝐴 − ((𝐴↑3) / 6)) ∈ ℂ) → (i · (𝐴 − ((𝐴↑3) / 6))) ∈ ℂ) | |
27 | 13, 25, 26 | sylancr 587 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (i · (𝐴 − ((𝐴↑3) / 6))) ∈ ℂ) |
28 | 12, 27 | addcld 11174 | . . . 4 ⊢ (𝐴 ∈ ℝ → ((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6)))) ∈ ℂ) |
29 | mulcl 11135 | . . . . . 6 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (i · 𝐴) ∈ ℂ) | |
30 | 13, 2, 29 | sylancr 587 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (i · 𝐴) ∈ ℂ) |
31 | 4nn0 12432 | . . . . 5 ⊢ 4 ∈ ℕ0 | |
32 | 3 | eftlcl 15989 | . . . . 5 ⊢ (((i · 𝐴) ∈ ℂ ∧ 4 ∈ ℕ0) → Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘) ∈ ℂ) |
33 | 30, 31, 32 | sylancl 586 | . . . 4 ⊢ (𝐴 ∈ ℝ → Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘) ∈ ℂ) |
34 | 28, 33 | readdd 15099 | . . 3 ⊢ (𝐴 ∈ ℝ → (ℜ‘(((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6)))) + Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘))) = ((ℜ‘((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6))))) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
35 | 11, 24 | crred 15116 | . . . 4 ⊢ (𝐴 ∈ ℝ → (ℜ‘((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6))))) = (1 − ((𝐴↑2) / 2))) |
36 | 35 | oveq1d 7372 | . . 3 ⊢ (𝐴 ∈ ℝ → ((ℜ‘((1 − ((𝐴↑2) / 2)) + (i · (𝐴 − ((𝐴↑3) / 6))))) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘))) = ((1 − ((𝐴↑2) / 2)) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
37 | 6, 34, 36 | 3eqtrd 2780 | . 2 ⊢ (𝐴 ∈ ℝ → (ℜ‘(exp‘(i · 𝐴))) = ((1 − ((𝐴↑2) / 2)) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
38 | 1, 37 | eqtrd 2776 | 1 ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = ((1 − ((𝐴↑2) / 2)) + (ℜ‘Σ𝑘 ∈ (ℤ≥‘4)(𝐹‘𝑘)))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1541 ∈ wcel 2106 ≠ wne 2943 ↦ cmpt 5188 ‘cfv 6496 (class class class)co 7357 ℂcc 11049 ℝcr 11050 0cc0 11051 1c1 11052 ici 11053 + caddc 11054 · cmul 11056 − cmin 11385 / cdiv 11812 2c2 12208 3c3 12209 4c4 12210 6c6 12212 ℕ0cn0 12413 ℤ≥cuz 12763 ↑cexp 13967 !cfa 14173 ℜcre 14982 Σcsu 15570 expce 15944 cosccos 15947 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2707 ax-rep 5242 ax-sep 5256 ax-nul 5263 ax-pow 5320 ax-pr 5384 ax-un 7672 ax-inf2 9577 ax-cnex 11107 ax-resscn 11108 ax-1cn 11109 ax-icn 11110 ax-addcl 11111 ax-addrcl 11112 ax-mulcl 11113 ax-mulrcl 11114 ax-mulcom 11115 ax-addass 11116 ax-mulass 11117 ax-distr 11118 ax-i2m1 11119 ax-1ne0 11120 ax-1rid 11121 ax-rnegex 11122 ax-rrecex 11123 ax-cnre 11124 ax-pre-lttri 11125 ax-pre-lttrn 11126 ax-pre-ltadd 11127 ax-pre-mulgt0 11128 ax-pre-sup 11129 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2538 df-eu 2567 df-clab 2714 df-cleq 2728 df-clel 2814 df-nfc 2889 df-ne 2944 df-nel 3050 df-ral 3065 df-rex 3074 df-rmo 3353 df-reu 3354 df-rab 3408 df-v 3447 df-sbc 3740 df-csb 3856 df-dif 3913 df-un 3915 df-in 3917 df-ss 3927 df-pss 3929 df-nul 4283 df-if 4487 df-pw 4562 df-sn 4587 df-pr 4589 df-op 4593 df-uni 4866 df-int 4908 df-iun 4956 df-br 5106 df-opab 5168 df-mpt 5189 df-tr 5223 df-id 5531 df-eprel 5537 df-po 5545 df-so 5546 df-fr 5588 df-se 5589 df-we 5590 df-xp 5639 df-rel 5640 df-cnv 5641 df-co 5642 df-dm 5643 df-rn 5644 df-res 5645 df-ima 5646 df-pred 6253 df-ord 6320 df-on 6321 df-lim 6322 df-suc 6323 df-iota 6448 df-fun 6498 df-fn 6499 df-f 6500 df-f1 6501 df-fo 6502 df-f1o 6503 df-fv 6504 df-isom 6505 df-riota 7313 df-ov 7360 df-oprab 7361 df-mpo 7362 df-om 7803 df-1st 7921 df-2nd 7922 df-frecs 8212 df-wrecs 8243 df-recs 8317 df-rdg 8356 df-1o 8412 df-er 8648 df-pm 8768 df-en 8884 df-dom 8885 df-sdom 8886 df-fin 8887 df-sup 9378 df-inf 9379 df-oi 9446 df-card 9875 df-pnf 11191 df-mnf 11192 df-xr 11193 df-ltxr 11194 df-le 11195 df-sub 11387 df-neg 11388 df-div 11813 df-nn 12154 df-2 12216 df-3 12217 df-4 12218 df-5 12219 df-6 12220 df-n0 12414 df-z 12500 df-uz 12764 df-rp 12916 df-ico 13270 df-fz 13425 df-fzo 13568 df-fl 13697 df-seq 13907 df-exp 13968 df-fac 14174 df-hash 14231 df-shft 14952 df-cj 14984 df-re 14985 df-im 14986 df-sqrt 15120 df-abs 15121 df-limsup 15353 df-clim 15370 df-rlim 15371 df-sum 15571 df-ef 15950 df-cos 15953 |
This theorem is referenced by: cos01bnd 16068 |
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