cos2x+sin²x = 0,75
cos²x - sin²x + sin²x = 0.75
cos²x = 0.75
cosx = ±√0.75 = ±0.5√3
1) cosx = -0.5√3
x₁ = 5π/6 + 2πn
x₂ = -5π/6 + 2πn
n =1 x₁ = (2 + 5/6) π x∉[π; 5π/2]
x₂ = (2- 5/6) π = 7π/6 x∈[π; 5π/2]
n =2 x₁ = (4 + 5/6) π x∉[π; 5π/2]
x₂ = (4- 5/6) π x∉[π; 5π/2]
2) cosx = 0.5√3
x₁ = π/6 + 2πn
x₂ = -π/6 + 2πn
n =1 x₁ = (2 + 1/6) π = 13π/6 x∈[π; 5π/2]
x₂ = (2 - 1/6) π = 11π/6 x∈[π; 5π/2]
n =2 x₁ = (4 + 1/6) π x∉[π; 5π/2]
x₂ = (4- 1/6) π x∉[π; 5π/2]
Ответ: x = 7π/6; 11π/6; 13π/6
<span>1) 54-18= 36(осталось). 2) 36+54= 90(км). Ответ: 90 км</span>
Ответ
1) Х = 1362 2) Х = 10152
Пошаговое объяснение:
1) (Х + 3) х 5 = 6825 2) 5859 : 7 + Х = 10989
5Х + 15 = 6825 837 + Х = 10989
5Х = 15 = 6825 Х = 10989 - 837
Х = 1362 Х = 10152
9•2=18
3•3=9
18+9=27
Ответ: 18 двухколёсных и 9 трёхколёсных велосипедов было в детском мире.