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Mirrors > Home > MPE Home > Th. List > recosval | Structured version Visualization version GIF version |
Description: The cosine of a real number in terms of the exponential function. (Contributed by NM, 30-Apr-2005.) |
Ref | Expression |
---|---|
recosval | ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = (ℜ‘(exp‘(i · 𝐴)))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-icn 11212 | . . . . . . . 8 ⊢ i ∈ ℂ | |
2 | recn 11243 | . . . . . . . 8 ⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℂ) | |
3 | cjmul 15178 | . . . . . . . 8 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (∗‘(i · 𝐴)) = ((∗‘i) · (∗‘𝐴))) | |
4 | 1, 2, 3 | sylancr 587 | . . . . . . 7 ⊢ (𝐴 ∈ ℝ → (∗‘(i · 𝐴)) = ((∗‘i) · (∗‘𝐴))) |
5 | cji 15195 | . . . . . . . . 9 ⊢ (∗‘i) = -i | |
6 | 5 | oveq1i 7441 | . . . . . . . 8 ⊢ ((∗‘i) · (∗‘𝐴)) = (-i · (∗‘𝐴)) |
7 | cjre 15175 | . . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → (∗‘𝐴) = 𝐴) | |
8 | 7 | oveq2d 7447 | . . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (-i · (∗‘𝐴)) = (-i · 𝐴)) |
9 | 6, 8 | eqtrid 2787 | . . . . . . 7 ⊢ (𝐴 ∈ ℝ → ((∗‘i) · (∗‘𝐴)) = (-i · 𝐴)) |
10 | 4, 9 | eqtrd 2775 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → (∗‘(i · 𝐴)) = (-i · 𝐴)) |
11 | 10 | fveq2d 6911 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (exp‘(∗‘(i · 𝐴))) = (exp‘(-i · 𝐴))) |
12 | mulcl 11237 | . . . . . . 7 ⊢ ((i ∈ ℂ ∧ 𝐴 ∈ ℂ) → (i · 𝐴) ∈ ℂ) | |
13 | 1, 2, 12 | sylancr 587 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → (i · 𝐴) ∈ ℂ) |
14 | efcj 16125 | . . . . . 6 ⊢ ((i · 𝐴) ∈ ℂ → (exp‘(∗‘(i · 𝐴))) = (∗‘(exp‘(i · 𝐴)))) | |
15 | 13, 14 | syl 17 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (exp‘(∗‘(i · 𝐴))) = (∗‘(exp‘(i · 𝐴)))) |
16 | 11, 15 | eqtr3d 2777 | . . . 4 ⊢ (𝐴 ∈ ℝ → (exp‘(-i · 𝐴)) = (∗‘(exp‘(i · 𝐴)))) |
17 | 16 | oveq2d 7447 | . . 3 ⊢ (𝐴 ∈ ℝ → ((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) = ((exp‘(i · 𝐴)) + (∗‘(exp‘(i · 𝐴))))) |
18 | 17 | oveq1d 7446 | . 2 ⊢ (𝐴 ∈ ℝ → (((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) / 2) = (((exp‘(i · 𝐴)) + (∗‘(exp‘(i · 𝐴)))) / 2)) |
19 | cosval 16156 | . . 3 ⊢ (𝐴 ∈ ℂ → (cos‘𝐴) = (((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) / 2)) | |
20 | 2, 19 | syl 17 | . 2 ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = (((exp‘(i · 𝐴)) + (exp‘(-i · 𝐴))) / 2)) |
21 | efcl 16115 | . . 3 ⊢ ((i · 𝐴) ∈ ℂ → (exp‘(i · 𝐴)) ∈ ℂ) | |
22 | reval 15142 | . . 3 ⊢ ((exp‘(i · 𝐴)) ∈ ℂ → (ℜ‘(exp‘(i · 𝐴))) = (((exp‘(i · 𝐴)) + (∗‘(exp‘(i · 𝐴)))) / 2)) | |
23 | 13, 21, 22 | 3syl 18 | . 2 ⊢ (𝐴 ∈ ℝ → (ℜ‘(exp‘(i · 𝐴))) = (((exp‘(i · 𝐴)) + (∗‘(exp‘(i · 𝐴)))) / 2)) |
24 | 18, 20, 23 | 3eqtr4d 2785 | 1 ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = (ℜ‘(exp‘(i · 𝐴)))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1537 ∈ wcel 2106 ‘cfv 6563 (class class class)co 7431 ℂcc 11151 ℝcr 11152 ici 11155 + caddc 11156 · cmul 11158 -cneg 11491 / cdiv 11918 2c2 12319 ∗ccj 15132 ℜcre 15133 expce 16094 cosccos 16097 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-10 2139 ax-11 2155 ax-12 2175 ax-ext 2706 ax-rep 5285 ax-sep 5302 ax-nul 5312 ax-pow 5371 ax-pr 5438 ax-un 7754 ax-inf2 9679 ax-cnex 11209 ax-resscn 11210 ax-1cn 11211 ax-icn 11212 ax-addcl 11213 ax-addrcl 11214 ax-mulcl 11215 ax-mulrcl 11216 ax-mulcom 11217 ax-addass 11218 ax-mulass 11219 ax-distr 11220 ax-i2m1 11221 ax-1ne0 11222 ax-1rid 11223 ax-rnegex 11224 ax-rrecex 11225 ax-cnre 11226 ax-pre-lttri 11227 ax-pre-lttrn 11228 ax-pre-ltadd 11229 ax-pre-mulgt0 11230 ax-pre-sup 11231 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-nf 1781 df-sb 2063 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2727 df-clel 2814 df-nfc 2890 df-ne 2939 df-nel 3045 df-ral 3060 df-rex 3069 df-rmo 3378 df-reu 3379 df-rab 3434 df-v 3480 df-sbc 3792 df-csb 3909 df-dif 3966 df-un 3968 df-in 3970 df-ss 3980 df-pss 3983 df-nul 4340 df-if 4532 df-pw 4607 df-sn 4632 df-pr 4634 df-op 4638 df-uni 4913 df-int 4952 df-iun 4998 df-br 5149 df-opab 5211 df-mpt 5232 df-tr 5266 df-id 5583 df-eprel 5589 df-po 5597 df-so 5598 df-fr 5641 df-se 5642 df-we 5643 df-xp 5695 df-rel 5696 df-cnv 5697 df-co 5698 df-dm 5699 df-rn 5700 df-res 5701 df-ima 5702 df-pred 6323 df-ord 6389 df-on 6390 df-lim 6391 df-suc 6392 df-iota 6516 df-fun 6565 df-fn 6566 df-f 6567 df-f1 6568 df-fo 6569 df-f1o 6570 df-fv 6571 df-isom 6572 df-riota 7388 df-ov 7434 df-oprab 7435 df-mpo 7436 df-om 7888 df-1st 8013 df-2nd 8014 df-frecs 8305 df-wrecs 8336 df-recs 8410 df-rdg 8449 df-1o 8505 df-er 8744 df-pm 8868 df-en 8985 df-dom 8986 df-sdom 8987 df-fin 8988 df-sup 9480 df-inf 9481 df-oi 9548 df-card 9977 df-pnf 11295 df-mnf 11296 df-xr 11297 df-ltxr 11298 df-le 11299 df-sub 11492 df-neg 11493 df-div 11919 df-nn 12265 df-2 12327 df-3 12328 df-n0 12525 df-z 12612 df-uz 12877 df-rp 13033 df-ico 13390 df-fz 13545 df-fzo 13692 df-fl 13829 df-seq 14040 df-exp 14100 df-fac 14310 df-hash 14367 df-shft 15103 df-cj 15135 df-re 15136 df-im 15137 df-sqrt 15271 df-abs 15272 df-limsup 15504 df-clim 15521 df-rlim 15522 df-sum 15720 df-ef 16100 df-cos 16103 |
This theorem is referenced by: recos4p 16172 recoscl 16174 cos0 16183 argregt0 26667 argrege0 26668 lawcos 26874 |
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