Cos4x*cosx+sin4x*sinx=0
cos(4x-x)=0
cos3x=0
3x=П/2+Пn
x=П/6+Пn/3
1) 1 - Ctg T = 1 - CosT\SinT = ( SinT - CosT) \ SinT
2) 1 - TgT = 1 - SinT\CosT = ( CosT - SinT) \ CosT
3) (SinT - CosT) \ SinT ) : ( CosT - SinT ) \ CosT = ( - CosT ) : SinT = ( - Ctg T)
А) 1; 3; 8.
б) 1/5; 7/9; 10/11.
в) 0,1; 0,2; 0,6.
X+2y=1 x=1-2y
x²-xy-2y²=1
(1-2y)²-(1-2y)*y-2y²=1
1-4y+4y²-y+2y²-2y²-1=0
4y²-5y=0
y*(4y-5)=0
y₁=0 x₁=1
4y-5=0
y₂=1,25 x₂=-1,5
Ответ: x₁=1 y₁=0 x₂=-1,5 y₂=1,25.