sincosq4sgn - Metamath Proof Explorer

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Theorem sincosq4sgn 25081

Description: The signs of the sine and cosine functions in the fourth quadrant. (Contributed by Paul Chapman, 24-Jan-2008.)

**Assertion**
Ref	Expression
sincosq4sgn	⊢ (𝐴 ∈ ((3 · (π / 2))(,)(2 · π)) → ((sin‘𝐴) < 0 ∧ 0 < (cos‘𝐴)))

**Proof of Theorem sincosq4sgn**
Step	Hyp	Ref	Expression
1		3re 11711	. . . . 5 ⊢ 3 ∈ ℝ
2		halfpire 25044	. . . . 5 ⊢ (π / 2) ∈ ℝ
3	1, 2	remulcli 10651	. . . 4 ⊢ (3 · (π / 2)) ∈ ℝ
4	3	rexri 10693	. . 3 ⊢ (3 · (π / 2)) ∈ ℝ^*
5		2re 11705	. . . . 5 ⊢ 2 ∈ ℝ
6		pire 25038	. . . . 5 ⊢ π ∈ ℝ
7	5, 6	remulcli 10651	. . . 4 ⊢ (2 · π) ∈ ℝ
8	7	rexri 10693	. . 3 ⊢ (2 · π) ∈ ℝ^*
9		elioo2 12773	. . 3 ⊢ (((3 · (π / 2)) ∈ ℝ^* ∧ (2 · π) ∈ ℝ^*) → (𝐴 ∈ ((3 · (π / 2))(,)(2 · π)) ↔ (𝐴 ∈ ℝ ∧ (3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π))))
10	4, 8, 9	mp2an 690	. 2 ⊢ (𝐴 ∈ ((3 · (π / 2))(,)(2 · π)) ↔ (𝐴 ∈ ℝ ∧ (3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)))
11		df-3 11695	. . . . . . . . . . . 12 ⊢ 3 = (2 + 1)
12	11	oveq1i 7160	. . . . . . . . . . 11 ⊢ (3 · (π / 2)) = ((2 + 1) · (π / 2))
13		2cn 11706	. . . . . . . . . . . 12 ⊢ 2 ∈ ℂ
14		ax-1cn 10589	. . . . . . . . . . . 12 ⊢ 1 ∈ ℂ
15	2	recni 10649	. . . . . . . . . . . 12 ⊢ (π / 2) ∈ ℂ
16	13, 14, 15	adddiri 10648	. . . . . . . . . . 11 ⊢ ((2 + 1) · (π / 2)) = ((2 · (π / 2)) + (1 · (π / 2)))
17	6	recni 10649	. . . . . . . . . . . . 13 ⊢ π ∈ ℂ
18		2ne0 11735	. . . . . . . . . . . . 13 ⊢ 2 ≠ 0
19	17, 13, 18	divcan2i 11377	. . . . . . . . . . . 12 ⊢ (2 · (π / 2)) = π
20	15	mulid2i 10640	. . . . . . . . . . . 12 ⊢ (1 · (π / 2)) = (π / 2)
21	19, 20	oveq12i 7162	. . . . . . . . . . 11 ⊢ ((2 · (π / 2)) + (1 · (π / 2))) = (π + (π / 2))
22	12, 16, 21	3eqtrri 2849	. . . . . . . . . 10 ⊢ (π + (π / 2)) = (3 · (π / 2))
23	22	breq1i 5065	. . . . . . . . 9 ⊢ ((π + (π / 2)) < 𝐴 ↔ (3 · (π / 2)) < 𝐴)
24		ltaddsub 11108	. . . . . . . . . 10 ⊢ ((π ∈ ℝ ∧ (π / 2) ∈ ℝ ∧ 𝐴 ∈ ℝ) → ((π + (π / 2)) < 𝐴 ↔ π < (𝐴 − (π / 2))))
25	6, 2, 24	mp3an12 1447	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → ((π + (π / 2)) < 𝐴 ↔ π < (𝐴 − (π / 2))))
26	23, 25	syl5bbr 287	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → ((3 · (π / 2)) < 𝐴 ↔ π < (𝐴 − (π / 2))))
27		ltsubadd 11104	. . . . . . . . . 10 ⊢ ((𝐴 ∈ ℝ ∧ (π / 2) ∈ ℝ ∧ (3 · (π / 2)) ∈ ℝ) → ((𝐴 − (π / 2)) < (3 · (π / 2)) ↔ 𝐴 < ((3 · (π / 2)) + (π / 2))))
28	2, 3, 27	mp3an23 1449	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → ((𝐴 − (π / 2)) < (3 · (π / 2)) ↔ 𝐴 < ((3 · (π / 2)) + (π / 2))))
29		df-4 11696	. . . . . . . . . . . . 13 ⊢ 4 = (3 + 1)
30	29	oveq1i 7160	. . . . . . . . . . . 12 ⊢ (4 · (π / 2)) = ((3 + 1) · (π / 2))
31	1	recni 10649	. . . . . . . . . . . . 13 ⊢ 3 ∈ ℂ
32	31, 14, 15	adddiri 10648	. . . . . . . . . . . 12 ⊢ ((3 + 1) · (π / 2)) = ((3 · (π / 2)) + (1 · (π / 2)))
33	20	oveq2i 7161	. . . . . . . . . . . 12 ⊢ ((3 · (π / 2)) + (1 · (π / 2))) = ((3 · (π / 2)) + (π / 2))
34	30, 32, 33	3eqtrri 2849	. . . . . . . . . . 11 ⊢ ((3 · (π / 2)) + (π / 2)) = (4 · (π / 2))
35		4cn 11716	. . . . . . . . . . . . 13 ⊢ 4 ∈ ℂ
36		2cnne0 11841	. . . . . . . . . . . . 13 ⊢ (2 ∈ ℂ ∧ 2 ≠ 0)
37		div12 11314	. . . . . . . . . . . . 13 ⊢ ((4 ∈ ℂ ∧ π ∈ ℂ ∧ (2 ∈ ℂ ∧ 2 ≠ 0)) → (4 · (π / 2)) = (π · (4 / 2)))
38	35, 17, 36, 37	mp3an 1457	. . . . . . . . . . . 12 ⊢ (4 · (π / 2)) = (π · (4 / 2))
39		4d2e2 11801	. . . . . . . . . . . . . 14 ⊢ (4 / 2) = 2
40	39	oveq2i 7161	. . . . . . . . . . . . 13 ⊢ (π · (4 / 2)) = (π · 2)
41	17, 13	mulcomi 10643	. . . . . . . . . . . . 13 ⊢ (π · 2) = (2 · π)
42	40, 41	eqtri 2844	. . . . . . . . . . . 12 ⊢ (π · (4 / 2)) = (2 · π)
43	38, 42	eqtri 2844	. . . . . . . . . . 11 ⊢ (4 · (π / 2)) = (2 · π)
44	34, 43	eqtri 2844	. . . . . . . . . 10 ⊢ ((3 · (π / 2)) + (π / 2)) = (2 · π)
45	44	breq2i 5066	. . . . . . . . 9 ⊢ (𝐴 < ((3 · (π / 2)) + (π / 2)) ↔ 𝐴 < (2 · π))
46	28, 45	syl6rbb 290	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (𝐴 < (2 · π) ↔ (𝐴 − (π / 2)) < (3 · (π / 2))))
47	26, 46	anbi12d 632	. . . . . . 7 ⊢ (𝐴 ∈ ℝ → (((3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) ↔ (π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2)))))
48		resubcl 10944	. . . . . . . . . 10 ⊢ ((𝐴 ∈ ℝ ∧ (π / 2) ∈ ℝ) → (𝐴 − (π / 2)) ∈ ℝ)
49	2, 48	mpan2 689	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → (𝐴 − (π / 2)) ∈ ℝ)
50	6	rexri 10693	. . . . . . . . . . 11 ⊢ π ∈ ℝ^*
51		elioo2 12773	. . . . . . . . . . 11 ⊢ ((π ∈ ℝ^* ∧ (3 · (π / 2)) ∈ ℝ^*) → ((𝐴 − (π / 2)) ∈ (π(,)(3 · (π / 2))) ↔ ((𝐴 − (π / 2)) ∈ ℝ ∧ π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2)))))
52	50, 4, 51	mp2an 690	. . . . . . . . . 10 ⊢ ((𝐴 − (π / 2)) ∈ (π(,)(3 · (π / 2))) ↔ ((𝐴 − (π / 2)) ∈ ℝ ∧ π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2))))
53		sincosq3sgn 25080	. . . . . . . . . 10 ⊢ ((𝐴 − (π / 2)) ∈ (π(,)(3 · (π / 2))) → ((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0))
54	52, 53	sylbir 237	. . . . . . . . 9 ⊢ (((𝐴 − (π / 2)) ∈ ℝ ∧ π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2))) → ((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0))
55	49, 54	syl3an1 1159	. . . . . . . 8 ⊢ ((𝐴 ∈ ℝ ∧ π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2))) → ((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0))
56	55	3expib 1118	. . . . . . 7 ⊢ (𝐴 ∈ ℝ → ((π < (𝐴 − (π / 2)) ∧ (𝐴 − (π / 2)) < (3 · (π / 2))) → ((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0)))
57	47, 56	sylbid 242	. . . . . 6 ⊢ (𝐴 ∈ ℝ → (((3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) → ((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0)))
58	49	resincld 15490	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (sin‘(𝐴 − (π / 2))) ∈ ℝ)
59	58	lt0neg1d 11203	. . . . . . 7 ⊢ (𝐴 ∈ ℝ → ((sin‘(𝐴 − (π / 2))) < 0 ↔ 0 < -(sin‘(𝐴 − (π / 2)))))
60	59	anbi1d 631	. . . . . 6 ⊢ (𝐴 ∈ ℝ → (((sin‘(𝐴 − (π / 2))) < 0 ∧ (cos‘(𝐴 − (π / 2))) < 0) ↔ (0 < -(sin‘(𝐴 − (π / 2))) ∧ (cos‘(𝐴 − (π / 2))) < 0)))
61	57, 60	sylibd 241	. . . . 5 ⊢ (𝐴 ∈ ℝ → (((3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) → (0 < -(sin‘(𝐴 − (π / 2))) ∧ (cos‘(𝐴 − (π / 2))) < 0)))
62		recn 10621	. . . . . . . . . 10 ⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℂ)
63		pncan3 10888	. . . . . . . . . 10 ⊢ (((π / 2) ∈ ℂ ∧ 𝐴 ∈ ℂ) → ((π / 2) + (𝐴 − (π / 2))) = 𝐴)
64	15, 62, 63	sylancr 589	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → ((π / 2) + (𝐴 − (π / 2))) = 𝐴)
65	64	fveq2d 6668	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (cos‘((π / 2) + (𝐴 − (π / 2)))) = (cos‘𝐴))
66	49	recnd 10663	. . . . . . . . 9 ⊢ (𝐴 ∈ ℝ → (𝐴 − (π / 2)) ∈ ℂ)
67		coshalfpip 25074	. . . . . . . . 9 ⊢ ((𝐴 − (π / 2)) ∈ ℂ → (cos‘((π / 2) + (𝐴 − (π / 2)))) = -(sin‘(𝐴 − (π / 2))))
68	66, 67	syl 17	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (cos‘((π / 2) + (𝐴 − (π / 2)))) = -(sin‘(𝐴 − (π / 2))))
69	65, 68	eqtr3d 2858	. . . . . . 7 ⊢ (𝐴 ∈ ℝ → (cos‘𝐴) = -(sin‘(𝐴 − (π / 2))))
70	69	breq2d 5070	. . . . . 6 ⊢ (𝐴 ∈ ℝ → (0 < (cos‘𝐴) ↔ 0 < -(sin‘(𝐴 − (π / 2)))))
71	64	fveq2d 6668	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (sin‘((π / 2) + (𝐴 − (π / 2)))) = (sin‘𝐴))
72		sinhalfpip 25072	. . . . . . . . 9 ⊢ ((𝐴 − (π / 2)) ∈ ℂ → (sin‘((π / 2) + (𝐴 − (π / 2)))) = (cos‘(𝐴 − (π / 2))))
73	66, 72	syl 17	. . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (sin‘((π / 2) + (𝐴 − (π / 2)))) = (cos‘(𝐴 − (π / 2))))
74	71, 73	eqtr3d 2858	. . . . . . 7 ⊢ (𝐴 ∈ ℝ → (sin‘𝐴) = (cos‘(𝐴 − (π / 2))))
75	74	breq1d 5068	. . . . . 6 ⊢ (𝐴 ∈ ℝ → ((sin‘𝐴) < 0 ↔ (cos‘(𝐴 − (π / 2))) < 0))
76	70, 75	anbi12d 632	. . . . 5 ⊢ (𝐴 ∈ ℝ → ((0 < (cos‘𝐴) ∧ (sin‘𝐴) < 0) ↔ (0 < -(sin‘(𝐴 − (π / 2))) ∧ (cos‘(𝐴 − (π / 2))) < 0)))
77	61, 76	sylibrd 261	. . . 4 ⊢ (𝐴 ∈ ℝ → (((3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) → (0 < (cos‘𝐴) ∧ (sin‘𝐴) < 0)))
78	77	3impib 1112	. . 3 ⊢ ((𝐴 ∈ ℝ ∧ (3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) → (0 < (cos‘𝐴) ∧ (sin‘𝐴) < 0))
79	78	ancomd 464	. 2 ⊢ ((𝐴 ∈ ℝ ∧ (3 · (π / 2)) < 𝐴 ∧ 𝐴 < (2 · π)) → ((sin‘𝐴) < 0 ∧ 0 < (cos‘𝐴)))
80	10, 79	sylbi 219	1 ⊢ (𝐴 ∈ ((3 · (π / 2))(,)(2 · π)) → ((sin‘𝐴) < 0 ∧ 0 < (cos‘𝐴)))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∧ w3a 1083 = wceq 1533 ∈ wcel 2110 ≠ wne 3016 class class class wbr 5058 ‘cfv 6349 (class class class)co 7150 ℂcc 10529 ℝcr 10530 0cc0 10531 1c1 10532 + caddc 10534 · cmul 10536 ℝ^*cxr 10668 < clt 10669 − cmin 10864 -cneg 10865 / cdiv 11291 2c2 11686 3c3 11687 4c4 11688 (,)cioo 12732 sincsin 15411 cosccos 15412 πcpi 15414

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 1907 ax-6 1966 ax-7 2011 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2157 ax-12 2173 ax-ext 2793 ax-rep 5182 ax-sep 5195 ax-nul 5202 ax-pow 5258 ax-pr 5321 ax-un 7455 ax-inf2 9098 ax-cnex 10587 ax-resscn 10588 ax-1cn 10589 ax-icn 10590 ax-addcl 10591 ax-addrcl 10592 ax-mulcl 10593 ax-mulrcl 10594 ax-mulcom 10595 ax-addass 10596 ax-mulass 10597 ax-distr 10598 ax-i2m1 10599 ax-1ne0 10600 ax-1rid 10601 ax-rnegex 10602 ax-rrecex 10603 ax-cnre 10604 ax-pre-lttri 10605 ax-pre-lttrn 10606 ax-pre-ltadd 10607 ax-pre-mulgt0 10608 ax-pre-sup 10609 ax-addf 10610 ax-mulf 10611

This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1536 df-fal 1546 df-ex 1777 df-nf 1781 df-sb 2066 df-mo 2618 df-eu 2650 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3496 df-sbc 3772 df-csb 3883 df-dif 3938 df-un 3940 df-in 3942 df-ss 3951 df-pss 3953 df-nul 4291 df-if 4467 df-pw 4540 df-sn 4561 df-pr 4563 df-tp 4565 df-op 4567 df-uni 4832 df-int 4869 df-iun 4913 df-iin 4914 df-br 5059 df-opab 5121 df-mpt 5139 df-tr 5165 df-id 5454 df-eprel 5459 df-po 5468 df-so 5469 df-fr 5508 df-se 5509 df-we 5510 df-xp 5555 df-rel 5556 df-cnv 5557 df-co 5558 df-dm 5559 df-rn 5560 df-res 5561 df-ima 5562 df-pred 6142 df-ord 6188 df-on 6189 df-lim 6190 df-suc 6191 df-iota 6308 df-fun 6351 df-fn 6352 df-f 6353 df-f1 6354 df-fo 6355 df-f1o 6356 df-fv 6357 df-isom 6358 df-riota 7108 df-ov 7153 df-oprab 7154 df-mpo 7155 df-of 7403 df-om 7575 df-1st 7683 df-2nd 7684 df-supp 7825 df-wrecs 7941 df-recs 8002 df-rdg 8040 df-1o 8096 df-2o 8097 df-oadd 8100 df-er 8283 df-map 8402 df-pm 8403 df-ixp 8456 df-en 8504 df-dom 8505 df-sdom 8506 df-fin 8507 df-fsupp 8828 df-fi 8869 df-sup 8900 df-inf 8901 df-oi 8968 df-card 9362 df-pnf 10671 df-mnf 10672 df-xr 10673 df-ltxr 10674 df-le 10675 df-sub 10866 df-neg 10867 df-div 11292 df-nn 11633 df-2 11694 df-3 11695 df-4 11696 df-5 11697 df-6 11698 df-7 11699 df-8 11700 df-9 11701 df-n0 11892 df-z 11976 df-dec 12093 df-uz 12238 df-q 12343 df-rp 12384 df-xneg 12501 df-xadd 12502 df-xmul 12503 df-ioo 12736 df-ioc 12737 df-ico 12738 df-icc 12739 df-fz 12887 df-fzo 13028 df-fl 13156 df-seq 13364 df-exp 13424 df-fac 13628 df-bc 13657 df-hash 13685 df-shft 14420 df-cj 14452 df-re 14453 df-im 14454 df-sqrt 14588 df-abs 14589 df-limsup 14822 df-clim 14839 df-rlim 14840 df-sum 15037 df-ef 15415 df-sin 15417 df-cos 15418 df-pi 15420 df-struct 16479 df-ndx 16480 df-slot 16481 df-base 16483 df-sets 16484 df-ress 16485 df-plusg 16572 df-mulr 16573 df-starv 16574 df-sca 16575 df-vsca 16576 df-ip 16577 df-tset 16578 df-ple 16579 df-ds 16581 df-unif 16582 df-hom 16583 df-cco 16584 df-rest 16690 df-topn 16691 df-0g 16709 df-gsum 16710 df-topgen 16711 df-pt 16712 df-prds 16715 df-xrs 16769 df-qtop 16774 df-imas 16775 df-xps 16777 df-mre 16851 df-mrc 16852 df-acs 16854 df-mgm 17846 df-sgrp 17895 df-mnd 17906 df-submnd 17951 df-mulg 18219 df-cntz 18441 df-cmn 18902 df-psmet 20531 df-xmet 20532 df-met 20533 df-bl 20534 df-mopn 20535 df-fbas 20536 df-fg 20537 df-cnfld 20540 df-top 21496 df-topon 21513 df-topsp 21535 df-bases 21548 df-cld 21621 df-ntr 21622 df-cls 21623 df-nei 21700 df-lp 21738 df-perf 21739 df-cn 21829 df-cnp 21830 df-haus 21917 df-tx 22164 df-hmeo 22357 df-fil 22448 df-fm 22540 df-flim 22541 df-flf 22542 df-xms 22924 df-ms 22925 df-tms 22926 df-cncf 23480 df-limc 24458 df-dv 24459

This theorem is referenced by: (None)

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