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Theorem sincosq4sgn 13465
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  e.  ( ( 3  x.  ( pi  / 
2 ) ) (,) ( 2  x.  pi ) )  ->  (
( sin `  A
)  <  0  /\  0  <  ( cos `  A
) ) )

Proof of Theorem sincosq4sgn
StepHypRef Expression
1 3re 8939 . . . . 5  |-  3  e.  RR
2 halfpire 13428 . . . . 5  |-  ( pi 
/  2 )  e.  RR
31, 2remulcli 7921 . . . 4  |-  ( 3  x.  ( pi  / 
2 ) )  e.  RR
43rexri 7964 . . 3  |-  ( 3  x.  ( pi  / 
2 ) )  e. 
RR*
5 2re 8935 . . . . 5  |-  2  e.  RR
6 pire 13422 . . . . 5  |-  pi  e.  RR
75, 6remulcli 7921 . . . 4  |-  ( 2  x.  pi )  e.  RR
87rexri 7964 . . 3  |-  ( 2  x.  pi )  e. 
RR*
9 elioo2 9865 . . 3  |-  ( ( ( 3  x.  (
pi  /  2 ) )  e.  RR*  /\  (
2  x.  pi )  e.  RR* )  ->  ( A  e.  ( (
3  x.  ( pi 
/  2 ) ) (,) ( 2  x.  pi ) )  <->  ( A  e.  RR  /\  ( 3  x.  ( pi  / 
2 ) )  < 
A  /\  A  <  ( 2  x.  pi ) ) ) )
104, 8, 9mp2an 424 . 2  |-  ( A  e.  ( ( 3  x.  ( pi  / 
2 ) ) (,) ( 2  x.  pi ) )  <->  ( A  e.  RR  /\  ( 3  x.  ( pi  / 
2 ) )  < 
A  /\  A  <  ( 2  x.  pi ) ) )
11 df-3 8925 . . . . . . . . . . . 12  |-  3  =  ( 2  +  1 )
1211oveq1i 5860 . . . . . . . . . . 11  |-  ( 3  x.  ( pi  / 
2 ) )  =  ( ( 2  +  1 )  x.  (
pi  /  2 ) )
13 2cn 8936 . . . . . . . . . . . 12  |-  2  e.  CC
14 ax-1cn 7854 . . . . . . . . . . . 12  |-  1  e.  CC
152recni 7919 . . . . . . . . . . . 12  |-  ( pi 
/  2 )  e.  CC
1613, 14, 15adddiri 7918 . . . . . . . . . . 11  |-  ( ( 2  +  1 )  x.  ( pi  / 
2 ) )  =  ( ( 2  x.  ( pi  /  2
) )  +  ( 1  x.  ( pi 
/  2 ) ) )
176recni 7919 . . . . . . . . . . . . 13  |-  pi  e.  CC
18 2ap0 8958 . . . . . . . . . . . . 13  |-  2 #  0
1917, 13, 18divcanap2i 8659 . . . . . . . . . . . 12  |-  ( 2  x.  ( pi  / 
2 ) )  =  pi
2015mulid2i 7910 . . . . . . . . . . . 12  |-  ( 1  x.  ( pi  / 
2 ) )  =  ( pi  /  2
)
2119, 20oveq12i 5862 . . . . . . . . . . 11  |-  ( ( 2  x.  ( pi 
/  2 ) )  +  ( 1  x.  ( pi  /  2
) ) )  =  ( pi  +  ( pi  /  2 ) )
2212, 16, 213eqtrri 2196 . . . . . . . . . 10  |-  ( pi  +  ( pi  / 
2 ) )  =  ( 3  x.  (
pi  /  2 ) )
2322breq1i 3994 . . . . . . . . 9  |-  ( ( pi  +  ( pi 
/  2 ) )  <  A  <->  ( 3  x.  ( pi  / 
2 ) )  < 
A )
24 ltaddsub 8342 . . . . . . . . . 10  |-  ( ( pi  e.  RR  /\  ( pi  /  2
)  e.  RR  /\  A  e.  RR )  ->  ( ( pi  +  ( pi  /  2
) )  <  A  <->  pi 
<  ( A  -  ( pi  /  2
) ) ) )
256, 2, 24mp3an12 1322 . . . . . . . . 9  |-  ( A  e.  RR  ->  (
( pi  +  ( pi  /  2 ) )  <  A  <->  pi  <  ( A  -  ( pi 
/  2 ) ) ) )
2623, 25bitr3id 193 . . . . . . . 8  |-  ( A  e.  RR  ->  (
( 3  x.  (
pi  /  2 ) )  <  A  <->  pi  <  ( A  -  ( pi 
/  2 ) ) ) )
27 ltsubadd 8338 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  ( pi  /  2
)  e.  RR  /\  ( 3  x.  (
pi  /  2 ) )  e.  RR )  ->  ( ( A  -  ( pi  / 
2 ) )  < 
( 3  x.  (
pi  /  2 ) )  <->  A  <  ( ( 3  x.  ( pi 
/  2 ) )  +  ( pi  / 
2 ) ) ) )
282, 3, 27mp3an23 1324 . . . . . . . . 9  |-  ( A  e.  RR  ->  (
( A  -  (
pi  /  2 ) )  <  ( 3  x.  ( pi  / 
2 ) )  <->  A  <  ( ( 3  x.  (
pi  /  2 ) )  +  ( pi 
/  2 ) ) ) )
29 df-4 8926 . . . . . . . . . . . . 13  |-  4  =  ( 3  +  1 )
3029oveq1i 5860 . . . . . . . . . . . 12  |-  ( 4  x.  ( pi  / 
2 ) )  =  ( ( 3  +  1 )  x.  (
pi  /  2 ) )
311recni 7919 . . . . . . . . . . . . 13  |-  3  e.  CC
3231, 14, 15adddiri 7918 . . . . . . . . . . . 12  |-  ( ( 3  +  1 )  x.  ( pi  / 
2 ) )  =  ( ( 3  x.  ( pi  /  2
) )  +  ( 1  x.  ( pi 
/  2 ) ) )
3320oveq2i 5861 . . . . . . . . . . . 12  |-  ( ( 3  x.  ( pi 
/  2 ) )  +  ( 1  x.  ( pi  /  2
) ) )  =  ( ( 3  x.  ( pi  /  2
) )  +  ( pi  /  2 ) )
3430, 32, 333eqtrri 2196 . . . . . . . . . . 11  |-  ( ( 3  x.  ( pi 
/  2 ) )  +  ( pi  / 
2 ) )  =  ( 4  x.  (
pi  /  2 ) )
35 4cn 8943 . . . . . . . . . . . . 13  |-  4  e.  CC
3613, 18pm3.2i 270 . . . . . . . . . . . . 13  |-  ( 2  e.  CC  /\  2 #  0 )
37 div12ap 8598 . . . . . . . . . . . . 13  |-  ( ( 4  e.  CC  /\  pi  e.  CC  /\  (
2  e.  CC  /\  2 #  0 ) )  -> 
( 4  x.  (
pi  /  2 ) )  =  ( pi  x.  ( 4  / 
2 ) ) )
3835, 17, 36, 37mp3an 1332 . . . . . . . . . . . 12  |-  ( 4  x.  ( pi  / 
2 ) )  =  ( pi  x.  (
4  /  2 ) )
39 4d2e2 9025 . . . . . . . . . . . . . 14  |-  ( 4  /  2 )  =  2
4039oveq2i 5861 . . . . . . . . . . . . 13  |-  ( pi  x.  ( 4  / 
2 ) )  =  ( pi  x.  2 )
4117, 13mulcomi 7913 . . . . . . . . . . . . 13  |-  ( pi  x.  2 )  =  ( 2  x.  pi )
4240, 41eqtri 2191 . . . . . . . . . . . 12  |-  ( pi  x.  ( 4  / 
2 ) )  =  ( 2  x.  pi )
4338, 42eqtri 2191 . . . . . . . . . . 11  |-  ( 4  x.  ( pi  / 
2 ) )  =  ( 2  x.  pi )
4434, 43eqtri 2191 . . . . . . . . . 10  |-  ( ( 3  x.  ( pi 
/  2 ) )  +  ( pi  / 
2 ) )  =  ( 2  x.  pi )
4544breq2i 3995 . . . . . . . . 9  |-  ( A  <  ( ( 3  x.  ( pi  / 
2 ) )  +  ( pi  /  2
) )  <->  A  <  ( 2  x.  pi ) )
4628, 45bitr2di 196 . . . . . . . 8  |-  ( A  e.  RR  ->  ( A  <  ( 2  x.  pi )  <->  ( A  -  ( pi  / 
2 ) )  < 
( 3  x.  (
pi  /  2 ) ) ) )
4726, 46anbi12d 470 . . . . . . 7  |-  ( A  e.  RR  ->  (
( ( 3  x.  ( pi  /  2
) )  <  A  /\  A  <  ( 2  x.  pi ) )  <-> 
( pi  <  ( A  -  ( pi  /  2 ) )  /\  ( A  -  (
pi  /  2 ) )  <  ( 3  x.  ( pi  / 
2 ) ) ) ) )
48 resubcl 8170 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  ( pi  /  2
)  e.  RR )  ->  ( A  -  ( pi  /  2
) )  e.  RR )
492, 48mpan2 423 . . . . . . . . 9  |-  ( A  e.  RR  ->  ( A  -  ( pi  /  2 ) )  e.  RR )
506rexri 7964 . . . . . . . . . . 11  |-  pi  e.  RR*
51 elioo2 9865 . . . . . . . . . . 11  |-  ( ( pi  e.  RR*  /\  (
3  x.  ( pi 
/  2 ) )  e.  RR* )  ->  (
( A  -  (
pi  /  2 ) )  e.  ( pi
(,) ( 3  x.  ( pi  /  2
) ) )  <->  ( ( A  -  ( pi  /  2 ) )  e.  RR  /\  pi  <  ( A  -  ( pi 
/  2 ) )  /\  ( A  -  ( pi  /  2
) )  <  (
3  x.  ( pi 
/  2 ) ) ) ) )
5250, 4, 51mp2an 424 . . . . . . . . . 10  |-  ( ( A  -  ( pi 
/  2 ) )  e.  ( pi (,) ( 3  x.  (
pi  /  2 ) ) )  <->  ( ( A  -  ( pi  /  2 ) )  e.  RR  /\  pi  <  ( A  -  ( pi 
/  2 ) )  /\  ( A  -  ( pi  /  2
) )  <  (
3  x.  ( pi 
/  2 ) ) ) )
53 sincosq3sgn 13464 . . . . . . . . . 10  |-  ( ( A  -  ( pi 
/  2 ) )  e.  ( pi (,) ( 3  x.  (
pi  /  2 ) ) )  ->  (
( sin `  ( A  -  ( pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2
) ) )  <  0 ) )
5452, 53sylbir 134 . . . . . . . . 9  |-  ( ( ( A  -  (
pi  /  2 ) )  e.  RR  /\  pi  <  ( A  -  ( pi  /  2
) )  /\  ( A  -  ( pi  /  2 ) )  < 
( 3  x.  (
pi  /  2 ) ) )  ->  (
( sin `  ( A  -  ( pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2
) ) )  <  0 ) )
5549, 54syl3an1 1266 . . . . . . . 8  |-  ( ( A  e.  RR  /\  pi  <  ( A  -  ( pi  /  2
) )  /\  ( A  -  ( pi  /  2 ) )  < 
( 3  x.  (
pi  /  2 ) ) )  ->  (
( sin `  ( A  -  ( pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2
) ) )  <  0 ) )
56553expib 1201 . . . . . . 7  |-  ( A  e.  RR  ->  (
( pi  <  ( A  -  ( pi  /  2 ) )  /\  ( A  -  (
pi  /  2 ) )  <  ( 3  x.  ( pi  / 
2 ) ) )  ->  ( ( sin `  ( A  -  (
pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2 ) ) )  <  0 ) ) )
5747, 56sylbid 149 . . . . . 6  |-  ( A  e.  RR  ->  (
( ( 3  x.  ( pi  /  2
) )  <  A  /\  A  <  ( 2  x.  pi ) )  ->  ( ( sin `  ( A  -  (
pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2 ) ) )  <  0 ) ) )
5849resincld 11673 . . . . . . . 8  |-  ( A  e.  RR  ->  ( sin `  ( A  -  ( pi  /  2
) ) )  e.  RR )
5958lt0neg1d 8421 . . . . . . 7  |-  ( A  e.  RR  ->  (
( sin `  ( A  -  ( pi  /  2 ) ) )  <  0  <->  0  <  -u ( sin `  ( A  -  ( pi  /  2 ) ) ) ) )
6059anbi1d 462 . . . . . 6  |-  ( A  e.  RR  ->  (
( ( sin `  ( A  -  ( pi  /  2 ) ) )  <  0  /\  ( cos `  ( A  -  ( pi  /  2
) ) )  <  0 )  <->  ( 0  <  -u ( sin `  ( A  -  ( pi  /  2 ) ) )  /\  ( cos `  ( A  -  ( pi  /  2 ) ) )  <  0 ) ) )
6157, 60sylibd 148 . . . . 5  |-  ( A  e.  RR  ->  (
( ( 3  x.  ( pi  /  2
) )  <  A  /\  A  <  ( 2  x.  pi ) )  ->  ( 0  <  -u ( sin `  ( A  -  ( pi  /  2 ) ) )  /\  ( cos `  ( A  -  ( pi  /  2 ) ) )  <  0 ) ) )
62 recn 7894 . . . . . . . . . 10  |-  ( A  e.  RR  ->  A  e.  CC )
63 pncan3 8114 . . . . . . . . . 10  |-  ( ( ( pi  /  2
)  e.  CC  /\  A  e.  CC )  ->  ( ( pi  / 
2 )  +  ( A  -  ( pi 
/  2 ) ) )  =  A )
6415, 62, 63sylancr 412 . . . . . . . . 9  |-  ( A  e.  RR  ->  (
( pi  /  2
)  +  ( A  -  ( pi  / 
2 ) ) )  =  A )
6564fveq2d 5498 . . . . . . . 8  |-  ( A  e.  RR  ->  ( cos `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  =  ( cos `  A
) )
6649recnd 7935 . . . . . . . . 9  |-  ( A  e.  RR  ->  ( A  -  ( pi  /  2 ) )  e.  CC )
67 coshalfpip 13458 . . . . . . . . 9  |-  ( ( A  -  ( pi 
/  2 ) )  e.  CC  ->  ( cos `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  = 
-u ( sin `  ( A  -  ( pi  /  2 ) ) ) )
6866, 67syl 14 . . . . . . . 8  |-  ( A  e.  RR  ->  ( cos `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  = 
-u ( sin `  ( A  -  ( pi  /  2 ) ) ) )
6965, 68eqtr3d 2205 . . . . . . 7  |-  ( A  e.  RR  ->  ( cos `  A )  = 
-u ( sin `  ( A  -  ( pi  /  2 ) ) ) )
7069breq2d 3999 . . . . . 6  |-  ( A  e.  RR  ->  (
0  <  ( cos `  A )  <->  0  <  -u ( sin `  ( A  -  ( pi  /  2 ) ) ) ) )
7164fveq2d 5498 . . . . . . . 8  |-  ( A  e.  RR  ->  ( sin `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  =  ( sin `  A
) )
72 sinhalfpip 13456 . . . . . . . . 9  |-  ( ( A  -  ( pi 
/  2 ) )  e.  CC  ->  ( sin `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  =  ( cos `  ( A  -  ( pi  /  2 ) ) ) )
7366, 72syl 14 . . . . . . . 8  |-  ( A  e.  RR  ->  ( sin `  ( ( pi 
/  2 )  +  ( A  -  (
pi  /  2 ) ) ) )  =  ( cos `  ( A  -  ( pi  /  2 ) ) ) )
7471, 73eqtr3d 2205 . . . . . . 7  |-  ( A  e.  RR  ->  ( sin `  A )  =  ( cos `  ( A  -  ( pi  /  2 ) ) ) )
7574breq1d 3997 . . . . . 6  |-  ( A  e.  RR  ->  (
( sin `  A
)  <  0  <->  ( cos `  ( A  -  (
pi  /  2 ) ) )  <  0
) )
7670, 75anbi12d 470 . . . . 5  |-  ( A  e.  RR  ->  (
( 0  <  ( cos `  A )  /\  ( sin `  A )  <  0 )  <->  ( 0  <  -u ( sin `  ( A  -  ( pi  /  2 ) ) )  /\  ( cos `  ( A  -  ( pi  /  2 ) ) )  <  0 ) ) )
7761, 76sylibrd 168 . . . 4  |-  ( A  e.  RR  ->  (
( ( 3  x.  ( pi  /  2
) )  <  A  /\  A  <  ( 2  x.  pi ) )  ->  ( 0  < 
( cos `  A
)  /\  ( sin `  A )  <  0
) ) )
78773impib 1196 . . 3  |-  ( ( A  e.  RR  /\  ( 3  x.  (
pi  /  2 ) )  <  A  /\  A  <  ( 2  x.  pi ) )  -> 
( 0  <  ( cos `  A )  /\  ( sin `  A )  <  0 ) )
7978ancomd 265 . 2  |-  ( ( A  e.  RR  /\  ( 3  x.  (
pi  /  2 ) )  <  A  /\  A  <  ( 2  x.  pi ) )  -> 
( ( sin `  A
)  <  0  /\  0  <  ( cos `  A
) ) )
8010, 79sylbi 120 1  |-  ( A  e.  ( ( 3  x.  ( pi  / 
2 ) ) (,) ( 2  x.  pi ) )  ->  (
( sin `  A
)  <  0  /\  0  <  ( cos `  A
) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    <-> wb 104    /\ w3a 973    = wceq 1348    e. wcel 2141   class class class wbr 3987   ` cfv 5196  (class class class)co 5850   CCcc 7759   RRcr 7760   0cc0 7761   1c1 7762    + caddc 7764    x. cmul 7766   RR*cxr 7940    < clt 7941    - cmin 8077   -ucneg 8078   # cap 8487    / cdiv 8576   2c2 8916   3c3 8917   4c4 8918   (,)cioo 9832   sincsin 11594   cosccos 11595   picpi 11597
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 609  ax-in2 610  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-13 2143  ax-14 2144  ax-ext 2152  ax-coll 4102  ax-sep 4105  ax-nul 4113  ax-pow 4158  ax-pr 4192  ax-un 4416  ax-setind 4519  ax-iinf 4570  ax-cnex 7852  ax-resscn 7853  ax-1cn 7854  ax-1re 7855  ax-icn 7856  ax-addcl 7857  ax-addrcl 7858  ax-mulcl 7859  ax-mulrcl 7860  ax-addcom 7861  ax-mulcom 7862  ax-addass 7863  ax-mulass 7864  ax-distr 7865  ax-i2m1 7866  ax-0lt1 7867  ax-1rid 7868  ax-0id 7869  ax-rnegex 7870  ax-precex 7871  ax-cnre 7872  ax-pre-ltirr 7873  ax-pre-ltwlin 7874  ax-pre-lttrn 7875  ax-pre-apti 7876  ax-pre-ltadd 7877  ax-pre-mulgt0 7878  ax-pre-mulext 7879  ax-arch 7880  ax-caucvg 7881  ax-pre-suploc 7882  ax-addf 7883  ax-mulf 7884
This theorem depends on definitions:  df-bi 116  df-stab 826  df-dc 830  df-3or 974  df-3an 975  df-tru 1351  df-fal 1354  df-nf 1454  df-sb 1756  df-eu 2022  df-mo 2023  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-ne 2341  df-nel 2436  df-ral 2453  df-rex 2454  df-reu 2455  df-rmo 2456  df-rab 2457  df-v 2732  df-sbc 2956  df-csb 3050  df-dif 3123  df-un 3125  df-in 3127  df-ss 3134  df-nul 3415  df-if 3526  df-pw 3566  df-sn 3587  df-pr 3588  df-op 3590  df-uni 3795  df-int 3830  df-iun 3873  df-disj 3965  df-br 3988  df-opab 4049  df-mpt 4050  df-tr 4086  df-id 4276  df-po 4279  df-iso 4280  df-iord 4349  df-on 4351  df-ilim 4352  df-suc 4354  df-iom 4573  df-xp 4615  df-rel 4616  df-cnv 4617  df-co 4618  df-dm 4619  df-rn 4620  df-res 4621  df-ima 4622  df-iota 5158  df-fun 5198  df-fn 5199  df-f 5200  df-f1 5201  df-fo 5202  df-f1o 5203  df-fv 5204  df-isom 5205  df-riota 5806  df-ov 5853  df-oprab 5854  df-mpo 5855  df-of 6058  df-1st 6116  df-2nd 6117  df-recs 6281  df-irdg 6346  df-frec 6367  df-1o 6392  df-oadd 6396  df-er 6509  df-map 6624  df-pm 6625  df-en 6715  df-dom 6716  df-fin 6717  df-sup 6957  df-inf 6958  df-pnf 7943  df-mnf 7944  df-xr 7945  df-ltxr 7946  df-le 7947  df-sub 8079  df-neg 8080  df-reap 8481  df-ap 8488  df-div 8577  df-inn 8866  df-2 8924  df-3 8925  df-4 8926  df-5 8927  df-6 8928  df-7 8929  df-8 8930  df-9 8931  df-n0 9123  df-z 9200  df-uz 9475  df-q 9566  df-rp 9598  df-xneg 9716  df-xadd 9717  df-ioo 9836  df-ioc 9837  df-ico 9838  df-icc 9839  df-fz 9953  df-fzo 10086  df-seqfrec 10389  df-exp 10463  df-fac 10647  df-bc 10669  df-ihash 10697  df-shft 10766  df-cj 10793  df-re 10794  df-im 10795  df-rsqrt 10949  df-abs 10950  df-clim 11229  df-sumdc 11304  df-ef 11598  df-sin 11600  df-cos 11601  df-pi 11603  df-rest 12567  df-topgen 12586  df-psmet 12702  df-xmet 12703  df-met 12704  df-bl 12705  df-mopn 12706  df-top 12711  df-topon 12724  df-bases 12756  df-ntr 12811  df-cn 12903  df-cnp 12904  df-tx 12968  df-cncf 13273  df-limced 13340  df-dvap 13341
This theorem is referenced by: (None)
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