(sina-cosa)²=sin²a-2sinacosa+cos²a=1-2sinacosa=0.25
sina*cosa=(1-0.25)/2=0.375
1) 2Sin3x > -1
Sin3x > -1/2
-π/6 + 2πk < 3x < 7π/6 + 2πk , k ∈Z
-π/18 +2πk/3 < x < 7π/18 + 2πk/3 , k ∈Z
2) Sin(x + П/4) ≤√2 /2
-5π/4 +2πk ≤ х+π/4 ≤ π/4 + 2πk , k ∈Z
-5π/4 +2πk - π/4 ≤ х ≤ π/4 + 2πk - π/4, k ∈Z
5π/4 +2πk - π/4 ≤ х ≤ 2πk , k ∈Z
3) Sin (x/4 - 3) < - √2/2
-3π/4 +2πk ≤ х/4 -3 ≤ -π/4 + 2πk , k ∈Z
-3π/4 +2πk +3 ≤ х ≤ -π/4 + 2πk +3, k ∈Z
4) tg(x/3 +√3) > -1
π/4 + πk < x/3 +√3 < π/2 + πk , k ∈Z
π/4 + πk - √3 < x/3 < π/2 + πk-√3, k ∈Z
3π/4 + 3πk < x < 3π/2 + 3πk , k ∈Z
370 т=370000 кг>3700 кг;7 км 560 м=7560 м>756 м
Две ручки стоят 10 рублей( 5+5)
три- 15 рублей(5+5+5)
четыре- 20 рублей(5+5+5+5)