Sin135°=sin(180°-135°)=sin45=√2/2
cos210°=cos(180°+30°)=-cos30°=-√3/2
sin300°=sin(360°-60°)=-sin60°=-√3/2
tg315°=tg(360°-45°)=-tg45°=-1
sin(-120°)=sin(180°-60°)=-sin60°=-√3/2
cos2Π/3=cos(3Π/3-Π/3)=cosΠ/3=1/2
tg5Π/6=tg(6Π/6-Π/6)=-tgΠ/6=-√3/3
{Y=2+x
{X^2+x•(2+x)=12
x^2+2x+x^2=12;
2x^2+2x-12=0; |:2
X^2+x-6=0;
D=1+24=25;
X1=(-1+5)/2=2;
X2=(-1-5)/2=-3;
Y1=2+2=4;
Y2=2-3=-1.
6
1)1/2sinx=2cosx
4sinxcosx=1
2sin2x=1
sin2x=1/2
2x=π/6+2πk U 2x=5π/6+2πk
x=π/12+πk U x=5π/12+πk,k∈z
2)cosx/sinx=3/2cosx
2cos²x=3sinx
3sinx-2+2sin²x=0
sinx=t
2t²+3t-2=0
D=9+16=25
t1=(-3-5)/4=-2⇒sinx=-2<-1 нет решения
t2=(-3+5)/4=1/2⇒sinx=1/2πx=π/6+2πk U x=5π/6+2πk,k∈z
7
1)(2x-1)/(x-1)=(3x+3)/(2x-1)
x≠0,5;x≠1
4x²-4x+1=3x²+3x-3x-3
4x²-4x+1-3x²+3=0
x²-4x+4=0
(x-2)²=0
x-2=0
x=2
2)(x+3)/(x+1)=(5x+3)/(x+3)
x≠-1;x≠-3
x²+3x+3x+9=5x²+5x+3x+3
4x²+2x-6=0
2x²+x-3=0
D=1+24=25
x1=(-1-5)/4=-1,5
x2=(-1+5)/4=1