<span>2sin 2n/3- ctg n/6 =2*(√3/2) - √3 = √3 - √3 = 0</span>
X=5y-4
(5y-4)^2+3y^2=4
25y^2-40y+16+3y^2-4=0
28y^2-40y+12=0 делим на 4
7y^2-10y+3=0
D=100-7*4*3=100-84=16
x=10+4/14=1 5y-1=4 5y=5 y=1
x=10-4/14=6/14=3/7 5y-3/7=4 5y=4+3/7 5y=31/7 y=31/35
Ответ:(1;1);(3/7;31/35)
Sin5x=1
5x = π/2 + 2πn, n∈Z
x = π/10 + 2πn/5 , n∈Z
1)2(√3/2sinx+1/2cosx)=√2
sin(x+π/6)=√2/2
x+π/6=(-1)^n*π/4+πn
x=(-1)^n*π/4-π/6+πn
2)sin²x+cos²-4sinxcosx-6cos²x=0
sin²x-4sinxcosx-5cos²x=0 /cos²x≠0
tg²x-4tgx-5=0
tgx=a
a²-4a-5=0
a1+a2=4 U a1*a2=-5⇒
a1=5⇒tgx=5⇒x=arctg5+πn
a2=-1⇒tgx=-1⇒x=-π/4+πn
3)sin²x+cos²+4sinxcosx+2cos²x=0
sin²x+4sinxcosx+3cos²x=0 /cos²x≠0
tg²x+4tgx+3=0
tgx=a
a²+4a+3=0
a1+a2=-4 U a1*a2=3⇒
a1=-3⇒tgx=-3⇒x=-arctg3+πn
a2=-1⇒tgx=-1⇒x=-π/4+πn
Смотри........................