Пошаговое объяснение:
1) 217 + 345
200 + 300 < 217 + 345 < 300 + 400
500 < 217 + 345 < 700
500 < 562 < 700
2)3564 + 5207
3000 + 5000 < 3564 + 5207 < 4000 + 6000
8000 < 3564 + 5207 < 10000
8000 < 8771 < 10000
3) 936 – 549
900 – 600 < 936 - 549 < 1000 – 500
300 < 387 < 500
4) 8718 – 4352
8000 – 5000 < 8718 – 4352 < 9000 – 4000
3000 < 4366 < 5000
5) 853 *47
800 * 40 < 853 *47 < 900 *50
32000 < 40091 < 45000
6) 5394 *736
5000 *700 < 5394 *736 < 6000 *800
3 500 000 < 3 969 984 < 4 800 000
7) 2952 : 36
2800 : 40 < 2952 : 36 < 3000 : 30
70 < 82 < 100
8) 36 924 : 68
35000 : 70 < 36 924 : 68 < 42000 : 60
500 < 543 < 700
Пошаговое объяснение:
1) 217 + 345
200 + 300 < 217 + 345 < 300 + 400
500 < 217 + 345 < 700
500 < 562 < 700
2)3564 + 5207
3000 + 5000 < 3564 + 5207 < 4000 + 6000
8000 < 3564 + 5207 < 10000
8000 < 8771 < 10000
3) 936 – 549
900 – 600 < 936 - 549 < 1000 – 500
300 < 387 < 500
4) 8718 – 4352
8000 – 5000 < 8718 – 4352 < 9000 – 4000
3000 < 4366 < 5000
5) 853 *47
800 * 40 < 853 *47 < 900 *50
32000 < 40091 < 45000
6) 5394 *736
5000 *700 < 5394 *736 < 6000 *800
3 500 000 < 3 969 984 < 4 800 000
7) 2952 : 36
2800 : 40 < 2952 : 36 < 3000 : 30
70 < 82 < 100
8) 36 924 : 68
35000 : 70 < 36 924 : 68 < 42000 : 60
500 < 543 < 700
1)
1/cos^2(a) – tg^2(a)-sin^2(a)=
=1/cos^2(a) – sin^2(a)/cos^2(a))-sin^2(a)=
=[1 – sin^2(a) ]/cos^2(a))-sin^2(a)=
=cos^2(a)/cos^2(a))-sin^2(a)=
=1--sin^2(a)=cos^2(a)
2)
cos^2(a)+ctg^2(a)-1/sin^2(a)=
=cos^2(a)+[cos^2(a)-1]/sin^2(a)=
=cos^2(a)-sin^2(a)]/sin^2(a)=
=cos^2(a)-1 = -sin^2(a)
3)
1/cos^2(a) – tg^2(a)(cos^2(a)+1)=
=1/cos^2(a) – sin^2(a)-sin^2(a)/(cos^2(a)=
=(1 – sin^2(a))/cos^2(a)-sin^2(a)=
=1-sin^2(a)=cos^2(a)