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Mirrors > Home > ILE Home > Th. List > cosneg | GIF version |
Description: The cosines of a number and its negative are the same. (Contributed by NM, 30-Apr-2005.) |
Ref | Expression |
---|---|
cosneg | ⊢ (𝐴 ∈ ℂ → (cos‘-𝐴) = (cos‘𝐴)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-icn 7720 | . . . . . . . 8 ⊢ i ∈ ℂ | |
2 | mulneg12 8164 | . . . . . . . 8 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (-i · 𝐴) = (i · -𝐴)) | |
3 | 1, 2 | mpan 420 | . . . . . . 7 ⊢ (𝐴 ∈ ℂ → (-i · 𝐴) = (i · -𝐴)) |
4 | 3 | eqcomd 2145 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → (i · -𝐴) = (-i · 𝐴)) |
5 | 4 | fveq2d 5425 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (exp‘(i · -𝐴)) = (exp‘(-i · 𝐴))) |
6 | mul2neg 8165 | . . . . . . 7 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (-i · -𝐴) = (i · 𝐴)) | |
7 | 1, 6 | mpan 420 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → (-i · -𝐴) = (i · 𝐴)) |
8 | 7 | fveq2d 5425 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (exp‘(-i · -𝐴)) = (exp‘(i · 𝐴))) |
9 | 5, 8 | oveq12d 5792 | . . . 4 ⊢ (𝐴 ∈ ℂ → ((exp‘(i · -𝐴)) + (exp‘(-i · -𝐴))) = ((exp‘(-i · 𝐴)) + (exp‘(i · 𝐴)))) |
10 | negicn 7968 | . . . . . . 7 ⊢ -i ∈ ℂ | |
11 | mulcl 7752 | . . . . . . 7 ⊢ ((-i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (-i · 𝐴) ∈ ℂ) | |
12 | 10, 11 | mpan 420 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → (-i · 𝐴) ∈ ℂ) |
13 | efcl 11375 | . . . . . 6 ⊢ ((-i · 𝐴) ∈ ℂ → (exp‘(-i · 𝐴)) ∈ ℂ) | |
14 | 12, 13 | syl 14 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (exp‘(-i · 𝐴)) ∈ ℂ) |
15 | mulcl 7752 | . . . . . . 7 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (i · 𝐴) ∈ ℂ) | |
16 | 1, 15 | mpan 420 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → (i · 𝐴) ∈ ℂ) |
17 | efcl 11375 | . . . . . 6 ⊢ ((i · 𝐴) ∈ ℂ → (exp‘(i · 𝐴)) ∈ ℂ) | |
18 | 16, 17 | syl 14 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (exp‘(i · 𝐴)) ∈ ℂ) |
19 | 14, 18 | addcomd 7918 | . . . 4 ⊢ (𝐴 ∈ ℂ → ((exp‘(-i · 𝐴)) + (exp‘(i · 𝐴))) = ((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴)))) |
20 | 9, 19 | eqtrd 2172 | . . 3 ⊢ (𝐴 ∈ ℂ → ((exp‘(i · -𝐴)) + (exp‘(-i · -𝐴))) = ((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴)))) |
21 | 20 | oveq1d 5789 | . 2 ⊢ (𝐴 ∈ ℂ → (((exp‘(i · -𝐴)) + (exp‘(-i · -𝐴))) / 2) = (((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) / 2)) |
22 | negcl 7967 | . . 3 ⊢ (𝐴 ∈ ℂ → -𝐴 ∈ ℂ) | |
23 | cosval 11415 | . . 3 ⊢ (-𝐴 ∈ ℂ → (cos‘-𝐴) = (((exp‘(i · -𝐴)) + (exp‘(-i · -𝐴))) / 2)) | |
24 | 22, 23 | syl 14 | . 2 ⊢ (𝐴 ∈ ℂ → (cos‘-𝐴) = (((exp‘(i · -𝐴)) + (exp‘(-i · -𝐴))) / 2)) |
25 | cosval 11415 | . 2 ⊢ (𝐴 ∈ ℂ → (cos‘𝐴) = (((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) / 2)) | |
26 | 21, 24, 25 | 3eqtr4d 2182 | 1 ⊢ (𝐴 ∈ ℂ → (cos‘-𝐴) = (cos‘𝐴)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 = wceq 1331 ∈ wcel 1480 ‘cfv 5123 (class class class)co 5774 ℂcc 7623 ici 7627 + caddc 7628 · cmul 7630 -cneg 7939 / cdiv 8437 2c2 8776 expce 11353 cosccos 11356 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-13 1491 ax-14 1492 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 ax-coll 4043 ax-sep 4046 ax-nul 4054 ax-pow 4098 ax-pr 4131 ax-un 4355 ax-setind 4452 ax-iinf 4502 ax-cnex 7716 ax-resscn 7717 ax-1cn 7718 ax-1re 7719 ax-icn 7720 ax-addcl 7721 ax-addrcl 7722 ax-mulcl 7723 ax-mulrcl 7724 ax-addcom 7725 ax-mulcom 7726 ax-addass 7727 ax-mulass 7728 ax-distr 7729 ax-i2m1 7730 ax-0lt1 7731 ax-1rid 7732 ax-0id 7733 ax-rnegex 7734 ax-precex 7735 ax-cnre 7736 ax-pre-ltirr 7737 ax-pre-ltwlin 7738 ax-pre-lttrn 7739 ax-pre-apti 7740 ax-pre-ltadd 7741 ax-pre-mulgt0 7742 ax-pre-mulext 7743 ax-arch 7744 ax-caucvg 7745 |
This theorem depends on definitions: df-bi 116 df-dc 820 df-3or 963 df-3an 964 df-tru 1334 df-fal 1337 df-nf 1437 df-sb 1736 df-eu 2002 df-mo 2003 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-ne 2309 df-nel 2404 df-ral 2421 df-rex 2422 df-reu 2423 df-rmo 2424 df-rab 2425 df-v 2688 df-sbc 2910 df-csb 3004 df-dif 3073 df-un 3075 df-in 3077 df-ss 3084 df-nul 3364 df-if 3475 df-pw 3512 df-sn 3533 df-pr 3534 df-op 3536 df-uni 3737 df-int 3772 df-iun 3815 df-br 3930 df-opab 3990 df-mpt 3991 df-tr 4027 df-id 4215 df-po 4218 df-iso 4219 df-iord 4288 df-on 4290 df-ilim 4291 df-suc 4293 df-iom 4505 df-xp 4545 df-rel 4546 df-cnv 4547 df-co 4548 df-dm 4549 df-rn 4550 df-res 4551 df-ima 4552 df-iota 5088 df-fun 5125 df-fn 5126 df-f 5127 df-f1 5128 df-fo 5129 df-f1o 5130 df-fv 5131 df-isom 5132 df-riota 5730 df-ov 5777 df-oprab 5778 df-mpo 5779 df-1st 6038 df-2nd 6039 df-recs 6202 df-irdg 6267 df-frec 6288 df-1o 6313 df-oadd 6317 df-er 6429 df-en 6635 df-dom 6636 df-fin 6637 df-pnf 7807 df-mnf 7808 df-xr 7809 df-ltxr 7810 df-le 7811 df-sub 7940 df-neg 7941 df-reap 8342 df-ap 8349 df-div 8438 df-inn 8726 df-2 8784 df-3 8785 df-4 8786 df-n0 8983 df-z 9060 df-uz 9332 df-q 9417 df-rp 9447 df-ico 9682 df-fz 9796 df-fzo 9925 df-seqfrec 10224 df-exp 10298 df-fac 10477 df-ihash 10527 df-cj 10619 df-re 10620 df-im 10621 df-rsqrt 10775 df-abs 10776 df-clim 11053 df-sumdc 11128 df-ef 11359 df-cos 11362 |
This theorem is referenced by: tannegap 11440 efmival 11445 sinsub 11452 cossub 11453 sincossq 11460 cosneghalfpi 12884 cos2pim 12900 ptolemy 12910 coseq0negpitopi 12922 cosq34lt1 12936 |
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