1
cosx=-1/2
x=+-2π/3+2πn U sinx<0⇒x=4π/3+2πn,n∈z<br>2
cosx=a
a²-4a+3=0
a1+a2=4 U a1*a2=3
a1=1⇒cosx=1⇒x=2πn,n∈z
a2=3⇒cosx=3>0 нет решения
3
sin3x>-1
х любое ,кроме х=-π/6+2πn/3,n∈z
4
sinxcosx=1/2⇒1/2sin2x=1/2⇒sin2x=1⇒2x=π/2πx=π/4
π/4-y=π/6⇒y=π/4-π/6=(3π-2π)/12=π/12
(π/4;π/12)
5
cosx=a
a²+3a>0
a(a+3)>0
a=0 a=-3
a<-3⇒cosx<-3 нет решения<br>a>0⇒cosx>0⇒x∈(-π/2+2πn;π/2+2πn,n∈z)
6
2sin3xcos2x+2cos3xcos2x=0
2cos2x(sin3x+cos3x)=0
cos2x=0⇒2x=π/2+πn⇒x=π/4+πn/2;n∈z
sin3x+cos3x=0/cos36x
tg3x+1=0
tg3x=-1⇒x=-π/4+πn,n∈z