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Theorem cosordlem 26695

Description: Lemma for cosord 26696. (Contributed by Mario Carneiro, 10-May-2014.)

**Hypotheses**
Ref	Expression
cosord.1	⊢ (𝜑 → 𝐴 ∈ (0[,]π))
cosord.2	⊢ (𝜑 → 𝐵 ∈ (0[,]π))
cosord.3	⊢ (𝜑 → 𝐴 < 𝐵)

**Assertion**
Ref	Expression
cosordlem	⊢ (𝜑 → (cos‘𝐵) < (cos‘𝐴))

**Proof of Theorem cosordlem**
Step	Hyp	Ref	Expression
1		cosord.2	. . . . . . 7 ⊢ (𝜑 → 𝐵 ∈ (0[,]π))
2		0re 11205	. . . . . . . 8 ⊢ 0 ∈ ℝ
3		pire 26619	. . . . . . . 8 ⊢ π ∈ ℝ
4	2, 3	elicc2i 13434	. . . . . . 7 ⊢ (𝐵 ∈ (0[,]π) ↔ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵 ∧ 𝐵 ≤ π))
5	1, 4	sylib 221	. . . . . 6 ⊢ (𝜑 → (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵 ∧ 𝐵 ≤ π))
6	5	simp1d 1160	. . . . 5 ⊢ (𝜑 → 𝐵 ∈ ℝ)
7	6	recnd 11232	. . . 4 ⊢ (𝜑 → 𝐵 ∈ ℂ)
8		cosord.1	. . . . . . 7 ⊢ (𝜑 → 𝐴 ∈ (0[,]π))
9	2, 3	elicc2i 13434	. . . . . . 7 ⊢ (𝐴 ∈ (0[,]π) ↔ (𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ∧ 𝐴 ≤ π))
10	8, 9	sylib 221	. . . . . 6 ⊢ (𝜑 → (𝐴 ∈ ℝ ∧ 0 ≤ 𝐴 ∧ 𝐴 ≤ π))
11	10	simp1d 1160	. . . . 5 ⊢ (𝜑 → 𝐴 ∈ ℝ)
12	11	recnd 11232	. . . 4 ⊢ (𝜑 → 𝐴 ∈ ℂ)
13		subcos 16226	. . . 4 ⊢ ((𝐵 ∈ ℂ ∧ 𝐴 ∈ ℂ) → ((cos‘𝐴) − (cos‘𝐵)) = (2 · ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2)))))
14	7, 12, 13	syl2anc 595	. . 3 ⊢ (𝜑 → ((cos‘𝐴) − (cos‘𝐵)) = (2 · ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2)))))
15		2rp 13016	. . . 4 ⊢ 2 ∈ ℝ⁺
16	6, 11	readdcld 11233	. . . . . . . 8 ⊢ (𝜑 → (𝐵 + 𝐴) ∈ ℝ)
17	16	rehalfcld 12486	. . . . . . 7 ⊢ (𝜑 → ((𝐵 + 𝐴) / 2) ∈ ℝ)
18	17	resincld 16194	. . . . . 6 ⊢ (𝜑 → (sin‘((𝐵 + 𝐴) / 2)) ∈ ℝ)
19	2	a1i 11	. . . . . . . . . . 11 ⊢ (𝜑 → 0 ∈ ℝ)
20	10	simp2d 1161	. . . . . . . . . . 11 ⊢ (𝜑 → 0 ≤ 𝐴)
21		cosord.3	. . . . . . . . . . 11 ⊢ (𝜑 → 𝐴 < 𝐵)
22	19, 11, 6, 20, 21	lelttrd 11363	. . . . . . . . . 10 ⊢ (𝜑 → 0 < 𝐵)
23	6, 11, 22, 20	addgtge0d 11783	. . . . . . . . 9 ⊢ (𝜑 → 0 < (𝐵 + 𝐴))
24		2re 12310	. . . . . . . . . 10 ⊢ 2 ∈ ℝ
25		2pos 12340	. . . . . . . . . 10 ⊢ 0 < 2
26		divgt0 12078	. . . . . . . . . 10 ⊢ ((((𝐵 + 𝐴) ∈ ℝ ∧ 0 < (𝐵 + 𝐴)) ∧ (2 ∈ ℝ ∧ 0 < 2)) → 0 < ((𝐵 + 𝐴) / 2))
27	24, 25, 26	mpanr12 717	. . . . . . . . 9 ⊢ (((𝐵 + 𝐴) ∈ ℝ ∧ 0 < (𝐵 + 𝐴)) → 0 < ((𝐵 + 𝐴) / 2))
28	16, 23, 27	syl2anc 595	. . . . . . . 8 ⊢ (𝜑 → 0 < ((𝐵 + 𝐴) / 2))
29	3	a1i 11	. . . . . . . . 9 ⊢ (𝜑 → π ∈ ℝ)
30	11, 6, 6, 21	ltadd2dd 11364	. . . . . . . . . . 11 ⊢ (𝜑 → (𝐵 + 𝐴) < (𝐵 + 𝐵))
31	7	2timesd 12482	. . . . . . . . . . 11 ⊢ (𝜑 → (2 · 𝐵) = (𝐵 + 𝐵))
32	30, 31	breqtrrd 5139	. . . . . . . . . 10 ⊢ (𝜑 → (𝐵 + 𝐴) < (2 · 𝐵))
33	24	a1i 11	. . . . . . . . . . 11 ⊢ (𝜑 → 2 ∈ ℝ)
34	25	a1i 11	. . . . . . . . . . 11 ⊢ (𝜑 → 0 < 2)
35		ltdivmul 12085	. . . . . . . . . . 11 ⊢ (((𝐵 + 𝐴) ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ (2 ∈ ℝ ∧ 0 < 2)) → (((𝐵 + 𝐴) / 2) < 𝐵 ↔ (𝐵 + 𝐴) < (2 · 𝐵)))
36	16, 6, 33, 34, 35	syl112anc 1401	. . . . . . . . . 10 ⊢ (𝜑 → (((𝐵 + 𝐴) / 2) < 𝐵 ↔ (𝐵 + 𝐴) < (2 · 𝐵)))
37	32, 36	mpbird 260	. . . . . . . . 9 ⊢ (𝜑 → ((𝐵 + 𝐴) / 2) < 𝐵)
38	5	simp3d 1162	. . . . . . . . 9 ⊢ (𝜑 → 𝐵 ≤ π)
39	17, 6, 29, 37, 38	ltletrd 11365	. . . . . . . 8 ⊢ (𝜑 → ((𝐵 + 𝐴) / 2) < π)
40		0xr 11251	. . . . . . . . 9 ⊢ 0 ∈ ℝ^*
41	3	rexri 11262	. . . . . . . . 9 ⊢ π ∈ ℝ^*
42		elioo2 13408	. . . . . . . . 9 ⊢ ((0 ∈ ℝ^* ∧ π ∈ ℝ^*) → (((𝐵 + 𝐴) / 2) ∈ (0(,)π) ↔ (((𝐵 + 𝐴) / 2) ∈ ℝ ∧ 0 < ((𝐵 + 𝐴) / 2) ∧ ((𝐵 + 𝐴) / 2) < π)))
43	40, 41, 42	mp2an 704	. . . . . . . 8 ⊢ (((𝐵 + 𝐴) / 2) ∈ (0(,)π) ↔ (((𝐵 + 𝐴) / 2) ∈ ℝ ∧ 0 < ((𝐵 + 𝐴) / 2) ∧ ((𝐵 + 𝐴) / 2) < π))
44	17, 28, 39, 43	syl3anbrc 1362	. . . . . . 7 ⊢ (𝜑 → ((𝐵 + 𝐴) / 2) ∈ (0(,)π))
45		sinq12gt0 26672	. . . . . . 7 ⊢ (((𝐵 + 𝐴) / 2) ∈ (0(,)π) → 0 < (sin‘((𝐵 + 𝐴) / 2)))
46	44, 45	syl 18	. . . . . 6 ⊢ (𝜑 → 0 < (sin‘((𝐵 + 𝐴) / 2)))
47	18, 46	elrpd 13052	. . . . 5 ⊢ (𝜑 → (sin‘((𝐵 + 𝐴) / 2)) ∈ ℝ⁺)
48	6, 11	resubcld 11637	. . . . . . . 8 ⊢ (𝜑 → (𝐵 − 𝐴) ∈ ℝ)
49	48	rehalfcld 12486	. . . . . . 7 ⊢ (𝜑 → ((𝐵 − 𝐴) / 2) ∈ ℝ)
50	49	resincld 16194	. . . . . 6 ⊢ (𝜑 → (sin‘((𝐵 − 𝐴) / 2)) ∈ ℝ)
51	11, 6	posdifd 11796	. . . . . . . . . 10 ⊢ (𝜑 → (𝐴 < 𝐵 ↔ 0 < (𝐵 − 𝐴)))
52	21, 51	mpbid 235	. . . . . . . . 9 ⊢ (𝜑 → 0 < (𝐵 − 𝐴))
53		divgt0 12078	. . . . . . . . . 10 ⊢ ((((𝐵 − 𝐴) ∈ ℝ ∧ 0 < (𝐵 − 𝐴)) ∧ (2 ∈ ℝ ∧ 0 < 2)) → 0 < ((𝐵 − 𝐴) / 2))
54	24, 25, 53	mpanr12 717	. . . . . . . . 9 ⊢ (((𝐵 − 𝐴) ∈ ℝ ∧ 0 < (𝐵 − 𝐴)) → 0 < ((𝐵 − 𝐴) / 2))
55	48, 52, 54	syl2anc 595	. . . . . . . 8 ⊢ (𝜑 → 0 < ((𝐵 − 𝐴) / 2))
56		rehalfcl 12466	. . . . . . . . . 10 ⊢ (π ∈ ℝ → (π / 2) ∈ ℝ)
57	3, 56	mp1i 14	. . . . . . . . 9 ⊢ (𝜑 → (π / 2) ∈ ℝ)
58	6, 11	subge02d 11801	. . . . . . . . . . . 12 ⊢ (𝜑 → (0 ≤ 𝐴 ↔ (𝐵 − 𝐴) ≤ 𝐵))
59	20, 58	mpbid 235	. . . . . . . . . . 11 ⊢ (𝜑 → (𝐵 − 𝐴) ≤ 𝐵)
60	48, 6, 29, 59, 38	letrd 11362	. . . . . . . . . 10 ⊢ (𝜑 → (𝐵 − 𝐴) ≤ π)
61		lediv1 12075	. . . . . . . . . . 11 ⊢ (((𝐵 − 𝐴) ∈ ℝ ∧ π ∈ ℝ ∧ (2 ∈ ℝ ∧ 0 < 2)) → ((𝐵 − 𝐴) ≤ π ↔ ((𝐵 − 𝐴) / 2) ≤ (π / 2)))
62	48, 29, 33, 34, 61	syl112anc 1401	. . . . . . . . . 10 ⊢ (𝜑 → ((𝐵 − 𝐴) ≤ π ↔ ((𝐵 − 𝐴) / 2) ≤ (π / 2)))
63	60, 62	mpbid 235	. . . . . . . . 9 ⊢ (𝜑 → ((𝐵 − 𝐴) / 2) ≤ (π / 2))
64		pirp 26626	. . . . . . . . . 10 ⊢ π ∈ ℝ⁺
65		rphalflt 13042	. . . . . . . . . 10 ⊢ (π ∈ ℝ⁺ → (π / 2) < π)
66	64, 65	mp1i 14	. . . . . . . . 9 ⊢ (𝜑 → (π / 2) < π)
67	49, 57, 29, 63, 66	lelttrd 11363	. . . . . . . 8 ⊢ (𝜑 → ((𝐵 − 𝐴) / 2) < π)
68		elioo2 13408	. . . . . . . . 9 ⊢ ((0 ∈ ℝ^* ∧ π ∈ ℝ^*) → (((𝐵 − 𝐴) / 2) ∈ (0(,)π) ↔ (((𝐵 − 𝐴) / 2) ∈ ℝ ∧ 0 < ((𝐵 − 𝐴) / 2) ∧ ((𝐵 − 𝐴) / 2) < π)))
69	40, 41, 68	mp2an 704	. . . . . . . 8 ⊢ (((𝐵 − 𝐴) / 2) ∈ (0(,)π) ↔ (((𝐵 − 𝐴) / 2) ∈ ℝ ∧ 0 < ((𝐵 − 𝐴) / 2) ∧ ((𝐵 − 𝐴) / 2) < π))
70	49, 55, 67, 69	syl3anbrc 1362	. . . . . . 7 ⊢ (𝜑 → ((𝐵 − 𝐴) / 2) ∈ (0(,)π))
71		sinq12gt0 26672	. . . . . . 7 ⊢ (((𝐵 − 𝐴) / 2) ∈ (0(,)π) → 0 < (sin‘((𝐵 − 𝐴) / 2)))
72	70, 71	syl 18	. . . . . 6 ⊢ (𝜑 → 0 < (sin‘((𝐵 − 𝐴) / 2)))
73	50, 72	elrpd 13052	. . . . 5 ⊢ (𝜑 → (sin‘((𝐵 − 𝐴) / 2)) ∈ ℝ⁺)
74	47, 73	rpmulcld 13071	. . . 4 ⊢ (𝜑 → ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2))) ∈ ℝ⁺)
75		rpmulcl 13036	. . . 4 ⊢ ((2 ∈ ℝ⁺ ∧ ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2))) ∈ ℝ⁺) → (2 · ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2)))) ∈ ℝ⁺)
76	15, 74, 75	sylancr 598	. . 3 ⊢ (𝜑 → (2 · ((sin‘((𝐵 + 𝐴) / 2)) · (sin‘((𝐵 − 𝐴) / 2)))) ∈ ℝ⁺)
77	14, 76	eqeltrd 2863	. 2 ⊢ (𝜑 → ((cos‘𝐴) − (cos‘𝐵)) ∈ ℝ⁺)
78	6	recoscld 16195	. . 3 ⊢ (𝜑 → (cos‘𝐵) ∈ ℝ)
79	11	recoscld 16195	. . 3 ⊢ (𝜑 → (cos‘𝐴) ∈ ℝ)
80		difrp 13051	. . 3 ⊢ (((cos‘𝐵) ∈ ℝ ∧ (cos‘𝐴) ∈ ℝ) → ((cos‘𝐵) < (cos‘𝐴) ↔ ((cos‘𝐴) − (cos‘𝐵)) ∈ ℝ⁺))
81	78, 79, 80	syl2anc 595	. 2 ⊢ (𝜑 → ((cos‘𝐵) < (cos‘𝐴) ↔ ((cos‘𝐴) − (cos‘𝐵)) ∈ ℝ⁺))
82	77, 81	mpbird 260	1 ⊢ (𝜑 → (cos‘𝐵) < (cos‘𝐴))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 209 ∧ wa 400 ∧ w3a 1103 = wceq 1570 ∈ wcel 2143 class class class wbr 5109 ‘cfv 6536 (class class class)co 7410 ℂcc 11093 ℝcr 11094 0cc0 11095 + caddc 11098 · cmul 11100 ℝ^*cxr 11237 < clt 11238 ≤ cle 11239 − cmin 11436 / cdiv 11866 2c2 12290 ℝ⁺crp 13011 (,)cioo 13367 [,]cicc 13370 sincsin 16112 cosccos 16113 πcpi 16115

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1825 ax-4 1839 ax-5 1940 ax-6 1997 ax-7 2038 ax-8 2145 ax-9 2153 ax-10 2176 ax-11 2192 ax-12 2213 ax-ext 2735 ax-rep 5238 ax-sep 5257 ax-nul 5269 ax-pow 5336 ax-pr 5404 ax-un 7732 ax-inf2 9606 ax-cnex 11151 ax-resscn 11152 ax-1cn 11153 ax-icn 11154 ax-addcl 11155 ax-addrcl 11156 ax-mulcl 11157 ax-mulrcl 11158 ax-mulcom 11159 ax-addass 11160 ax-mulass 11161 ax-distr 11162 ax-i2m1 11163 ax-1ne0 11164 ax-1rid 11165 ax-rnegex 11166 ax-rrecex 11167 ax-cnre 11168 ax-pre-lttri 11169 ax-pre-lttrn 11170 ax-pre-ltadd 11171 ax-pre-mulgt0 11172 ax-pre-sup 11173 ax-addf 11174

This theorem depends on definitions: df-bi 210 df-an 401 df-or 861 df-3or 1104 df-3an 1105 df-tru 1573 df-fal 1583 df-ex 1810 df-nf 1814 df-sb 2097 df-mo 2567 df-eu 2597 df-clab 2742 df-cleq 2755 df-clel 2838 df-nfc 2912 df-ne 2959 df-nel 3065 df-ral 3080 df-rex 3090 df-rmo 3369 df-reu 3370 df-rab 3417 df-v 3457 df-sbc 3745 df-csb 3854 df-dif 3908 df-un 3910 df-in 3912 df-ss 3922 df-pss 3925 df-nul 4287 df-if 4488 df-pw 4564 df-sn 4590 df-pr 4592 df-tp 4594 df-op 4596 df-uni 4873 df-int 4913 df-iun 4958 df-iin 4959 df-br 5110 df-opab 5174 df-mpt 5193 df-tr 5219 df-id 5556 df-eprel 5561 df-po 5569 df-so 5570 df-fr 5614 df-se 5615 df-we 5616 df-xp 5667 df-rel 5668 df-cnv 5669 df-co 5670 df-dm 5671 df-rn 5672 df-res 5673 df-ima 5674 df-pred 6302 df-ord 6363 df-on 6364 df-lim 6365 df-suc 6366 df-iota 6492 df-fun 6538 df-fn 6539 df-f 6540 df-f1 6541 df-fo 6542 df-f1o 6543 df-fv 6544 df-isom 6545 df-riota 7367 df-ov 7413 df-oprab 7414 df-mpo 7415 df-of 7674 df-om 7859 df-1st 7982 df-2nd 7983 df-supp 8153 df-frecs 8274 df-wrecs 8305 df-recs 8354 df-rdg 8393 df-1o 8449 df-2o 8450 df-er 8690 df-map 8822 df-pm 8823 df-ixp 8892 df-en 8940 df-dom 8941 df-sdom 8942 df-fin 8943 df-fsupp 9318 df-fi 9367 df-sup 9398 df-inf 9399 df-oi 9468 df-card 9921 df-pnf 11240 df-mnf 11241 df-xr 11242 df-ltxr 11243 df-le 11244 df-sub 11438 df-neg 11439 df-div 11867 df-nn 12229 df-2 12298 df-3 12299 df-4 12300 df-5 12301 df-6 12302 df-7 12303 df-8 12304 df-9 12305 df-n0 12500 df-z 12587 df-dec 12707 df-uz 12858 df-q 12968 df-rp 13012 df-xneg 13132 df-xadd 13133 df-xmul 13134 df-ioo 13371 df-ioc 13372 df-ico 13373 df-icc 13374 df-fz 13531 df-fzo 13679 df-fl 13821 df-seq 14034 df-exp 14094 df-fac 14306 df-bc 14335 df-hash 14363 df-shft 15100 df-cj 15146 df-re 15147 df-im 15148 df-sqrt 15282 df-abs 15283 df-limsup 15518 df-clim 15535 df-rlim 15536 df-sum 15734 df-ef 16116 df-sin 16118 df-cos 16119 df-pi 16121 df-struct 17202 df-sets 17219 df-slot 17237 df-ndx 17249 df-base 17265 df-ress 17286 df-plusg 17318 df-mulr 17319 df-starv 17320 df-sca 17321 df-vsca 17322 df-ip 17323 df-tset 17324 df-ple 17325 df-ds 17327 df-unif 17328 df-hom 17329 df-cco 17330 df-rest 17470 df-topn 17471 df-0g 17489 df-gsum 17490 df-topgen 17491 df-pt 17492 df-prds 17495 df-xrs 17551 df-qtop 17556 df-imas 17557 df-xps 17559 df-mre 17633 df-mrc 17634 df-acs 17636 df-mgm 18693 df-sgrp 18772 df-mnd 18788 df-submnd 18837 df-mulg 19129 df-cntz 19382 df-cmn 19847 df-psmet 21514 df-xmet 21515 df-met 21516 df-bl 21517 df-mopn 21518 df-fbas 21519 df-fg 21520 df-cnfld 21523 df-top 23051 df-topon 23068 df-topsp 23090 df-bases 23103 df-cld 23176 df-ntr 23177 df-cls 23178 df-nei 23255 df-lp 23293 df-perf 23294 df-cn 23384 df-cnp 23385 df-haus 23472 df-tx 23719 df-hmeo 23912 df-fil 24003 df-fm 24095 df-flim 24096 df-flf 24097 df-xms 24477 df-ms 24478 df-tms 24479 df-cncf 25037 df-limc 26025 df-dv 26026

This theorem is referenced by: cosord 26696 cos0pilt1 26697

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