Abs(sin(x))>Abs(cos(x)) (неравенство)
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Укажите решение неравенства: Abs(sin(x))>Abs(cos(x)) (множество решений неравенства)
Решение
Подробное решение
Дано неравенство:
∣sin(x)∣>∣cos(x)∣
Чтобы решить это нер-во - надо сначала решить соотвествующее ур-ние:
∣sin(x)∣=∣cos(x)∣
Решаем:
x1=−77.7544181763
x2=90.3207887907
x3=22.7765467385
x4=−93.4623814443
x5=77.7544181763
x6=−13.3517687778
x7=−71.4712328692
x8=33.7721210261
x9=−47.9092879672
x10=66.7588438888
x11=69.9004365424
x12=−25.9181393921
x13=63.6172512352
x14=30.6305283725
x15=−49.480084294
x16=84.0376034835
x17=−87.1791961371
x18=54.1924732744
x19=2.35619449019
x20=−33.7721210261
x21=10.2101761242
x22=62.0464549084
x23=76.1836218496
x24=49.480084294
x25=−2.35619449019
x26=−5.49778714378
x27=−55.7632696012
x28=60.4756585816
x29=−54.1924732744
x30=−38.4845100065
x31=−46.3384916404
x32=40.0553063333
x33=−96.6039740979
x34=41.6261026601
x35=−32.2013246993
x36=−79.3252145031
x37=−18.0641577581
x38=−62.0464549084
x39=44.7676953137
x40=46.3384916404
x41=−11.780972451
x42=27.4889357189
x43=−65.188047562
x44=71.4712328692
x45=85.6083998103
x46=32.2013246993
x47=74.6128255228
x48=−63.6172512352
x49=−76.1836218496
x50=18.0641577581
x51=−43.1968989869
x52=−99.7455667515
x53=−60.4756585816
x54=−90.3207887907
x55=−16.4933614313
x56=−69.9004365424
x57=88.7499924639
x58=3.92699081699
x59=93.4623814443
x60=11.780972451
x61=98.1747704247
x62=−19.6349540849
x63=38.4845100065
x64=−21.2057504117
x65=24.3473430653
x66=−84.0376034835
x67=−35.3429173529
x68=−41.6261026601
x69=−51.0508806208
x70=−91.8915851175
x71=82.4668071567
x72=0.785398163397
x73=96.6039740979
x74=25.9181393921
x75=−27.4889357189
x76=−24.3473430653
x77=−118.595122673
x78=−10.2101761242
x79=−40.0553063333
x80=−85.6083998103
x81=−57.334065928
x82=−98.1747704247
x83=47.9092879672
x84=16.4933614313
x85=−3.92699081699
x86=68.3296402156
x87=19.6349540849
x88=5.49778714378
x89=99.7455667515
x90=52.6216769476
x91=−68.3296402156
x92=55.7632696012
x93=91.8915851175
x94=8.63937979737
x95=−82.4668071567
x1=−77.7544181763
x2=90.3207887907
x3=22.7765467385
x4=−93.4623814443
x5=77.7544181763
x6=−13.3517687778
x7=−71.4712328692
x8=33.7721210261
x9=−47.9092879672
x10=66.7588438888
x11=69.9004365424
x12=−25.9181393921
x13=63.6172512352
x14=30.6305283725
x15=−49.480084294
x16=84.0376034835
x17=−87.1791961371
x18=54.1924732744
x19=2.35619449019
x20=−33.7721210261
x21=10.2101761242
x22=62.0464549084
x23=76.1836218496
x24=49.480084294
x25=−2.35619449019
x26=−5.49778714378
x27=−55.7632696012
x28=60.4756585816
x29=−54.1924732744
x30=−38.4845100065
x31=−46.3384916404
x32=40.0553063333
x33=−96.6039740979
x34=41.6261026601
x35=−32.2013246993
x36=−79.3252145031
x37=−18.0641577581
x38=−62.0464549084
x39=44.7676953137
x40=46.3384916404
x41=−11.780972451
x42=27.4889357189
x43=−65.188047562
x44=71.4712328692
x45=85.6083998103
x46=32.2013246993
x47=74.6128255228
x48=−63.6172512352
x49=−76.1836218496
x50=18.0641577581
x51=−43.1968989869
x52=−99.7455667515
x53=−60.4756585816
x54=−90.3207887907
x55=−16.4933614313
x56=−69.9004365424
x57=88.7499924639
x58=3.92699081699
x59=93.4623814443
x60=11.780972451
x61=98.1747704247
x62=−19.6349540849
x63=38.4845100065
x64=−21.2057504117
x65=24.3473430653
x66=−84.0376034835
x67=−35.3429173529
x68=−41.6261026601
x69=−51.0508806208
x70=−91.8915851175
x71=82.4668071567
x72=0.785398163397
x73=96.6039740979
x74=25.9181393921
x75=−27.4889357189
x76=−24.3473430653
x77=−118.595122673
x78=−10.2101761242
x79=−40.0553063333
x80=−85.6083998103
x81=−57.334065928
x82=−98.1747704247
x83=47.9092879672
x84=16.4933614313
x85=−3.92699081699
x86=68.3296402156
x87=19.6349540849
x88=5.49778714378
x89=99.7455667515
x90=52.6216769476
x91=−68.3296402156
x92=55.7632696012
x93=91.8915851175
x94=8.63937979737
x95=−82.4668071567
Данные корни
x77=−118.595122673
x52=−99.7455667515
x82=−98.1747704247
x33=−96.6039740979
x4=−93.4623814443
x70=−91.8915851175
x54=−90.3207887907
x17=−87.1791961371
x80=−85.6083998103
x66=−84.0376034835
x95=−82.4668071567
x36=−79.3252145031
x1=−77.7544181763
x49=−76.1836218496
x7=−71.4712328692
x56=−69.9004365424
x91=−68.3296402156
x43=−65.188047562
x48=−63.6172512352
x38=−62.0464549084
x53=−60.4756585816
x81=−57.334065928
x27=−55.7632696012
x29=−54.1924732744
x69=−51.0508806208
x15=−49.480084294
x9=−47.9092879672
x31=−46.3384916404
x51=−43.1968989869
x68=−41.6261026601
x79=−40.0553063333
x30=−38.4845100065
x67=−35.3429173529
x20=−33.7721210261
x35=−32.2013246993
x75=−27.4889357189
x12=−25.9181393921
x76=−24.3473430653
x64=−21.2057504117
x62=−19.6349540849
x37=−18.0641577581
x55=−16.4933614313
x6=−13.3517687778
x41=−11.780972451
x78=−10.2101761242
x26=−5.49778714378
x85=−3.92699081699
x25=−2.35619449019
x72=0.785398163397
x19=2.35619449019
x58=3.92699081699
x88=5.49778714378
x94=8.63937979737
x21=10.2101761242
x60=11.780972451
x84=16.4933614313
x50=18.0641577581
x87=19.6349540849
x3=22.7765467385
x65=24.3473430653
x74=25.9181393921
x42=27.4889357189
x14=30.6305283725
x46=32.2013246993
x8=33.7721210261
x63=38.4845100065
x32=40.0553063333
x34=41.6261026601
x39=44.7676953137
x40=46.3384916404
x83=47.9092879672
x24=49.480084294
x90=52.6216769476
x18=54.1924732744
x92=55.7632696012
x28=60.4756585816
x22=62.0464549084
x13=63.6172512352
x10=66.7588438888
x86=68.3296402156
x11=69.9004365424
x44=71.4712328692
x47=74.6128255228
x23=76.1836218496
x5=77.7544181763
x71=82.4668071567
x16=84.0376034835
x45=85.6083998103
x57=88.7499924639
x2=90.3207887907
x93=91.8915851175
x59=93.4623814443
x73=96.6039740979
x61=98.1747704247
x89=99.7455667515
являются точками смены знака неравенства в решениях.
Сначала определимся со знаком до крайней левой точки:
x0<x77
Возьмём например точку
x0=x77−101
=
−118.695122673
=
−118.695122673
подставляем в выражение
∣sin(x)∣>∣cos(x)∣
∣sin(−118.695122673)∣>∣cos(−118.695122673)∣
0.632981306688334 > 0.774167078467645
Тогда
x<−118.595122673
не выполняется
значит одно из решений нашего неравенства будет при:
x>−118.595122673∧x<−99.7455667515
_____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____
/ \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ /
-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------
x77 x52 x82 x33 x4 x70 x54 x17 x80 x66 x95 x36 x1 x49 x7 x56 x91 x43 x48 x38 x53 x81 x27 x29 x69 x15 x9 x31 x51 x68 x79 x30 x67 x20 x35 x75 x12 x76 x64 x62 x37 x55 x6 x41 x78 x26 x85 x25 x72 x19 x58 x88 x94 x21 x60 x84 x50 x87 x3 x65 x74 x42 x14 x46 x8 x63 x32 x34 x39 x40 x83 x24 x90 x18 x92 x28 x22 x13 x10 x86 x11 x44 x47 x23 x5 x71 x16 x45 x57 x2 x93 x59 x73 x61 x89
Другие решения неравенства будем получать переходом на следующий полюс
и т.д.
Ответ:
x>−118.595122673∧x<−99.7455667515
x>−98.1747704247∧x<−96.6039740979
x>−93.4623814443∧x<−91.8915851175
x>−90.3207887907∧x<−87.1791961371
x>−85.6083998103∧x<−84.0376034835
x>−82.4668071567∧x<−79.3252145031
x>−77.7544181763∧x<−76.1836218496
x>−71.4712328692∧x<−69.9004365424
x>−68.3296402156∧x<−65.188047562
x>−63.6172512352∧x<−62.0464549084
x>−60.4756585816∧x<−57.334065928
x>−55.7632696012∧x<−54.1924732744
x>−51.0508806208∧x<−49.480084294
x>−47.9092879672∧x<−46.3384916404
x>−43.1968989869∧x<−41.6261026601
x>−40.0553063333∧x<−38.4845100065
x>−35.3429173529∧x<−33.7721210261
x>−32.2013246993∧x<−27.4889357189
x>−25.9181393921∧x<−24.3473430653
x>−21.2057504117∧x<−19.6349540849
x>−18.0641577581∧x<−16.4933614313
x>−13.3517687778∧x<−11.780972451
x>−10.2101761242∧x<−5.49778714378
x>−3.92699081699∧x<−2.35619449019
x>0.785398163397∧x<2.35619449019
x>3.92699081699∧x<5.49778714378
x>8.63937979737∧x<10.2101761242
x>11.780972451∧x<16.4933614313
x>18.0641577581∧x<19.6349540849
x>22.7765467385∧x<24.3473430653
x>25.9181393921∧x<27.4889357189
x>30.6305283725∧x<32.2013246993
x>33.7721210261∧x<38.4845100065
x>40.0553063333∧x<41.6261026601
x>44.7676953137∧x<46.3384916404
x>47.9092879672∧x<49.480084294
x>52.6216769476∧x<54.1924732744
x>55.7632696012∧x<60.4756585816
x>62.0464549084∧x<63.6172512352
x>66.7588438888∧x<68.3296402156
x>69.9004365424∧x<71.4712328692
x>74.6128255228∧x<76.1836218496
x>77.7544181763∧x<82.4668071567
x>84.0376034835∧x<85.6083998103
x>88.7499924639∧x<90.3207887907
x>91.8915851175∧x<93.4623814443
x>96.6039740979∧x<98.1747704247
x>99.7455667515
Решение неравенства на графике
/ / -3*pi\ /-3*pi -pi \ /pi 3*pi\ /3*pi \\
Or|And|-oo < x, x < -----|, And|----- < x, x < ----|, And|-- < x, x < ----|, And|---- < x, x < oo||
\ \ 4 / \ 4 4 / \4 4 / \ 4 //
(−∞<x∧x<−43π)∨(−43π<x∧x<−4π)∨(4π<x∧x<43π)∨(43π<x∧x<∞) -3*pi -3*pi -pi pi 3*pi 3*pi
(-oo, -----) U (-----, ----) U (--, ----) U (----, oo)
4 4 4 4 4 4
x∈(−∞,−43π)∪(−43π,−4π)∪(4π,43π)∪(43π,∞)