1)1+cosx+cos(x/2)=0
2cos²(x/2)+cos(x/2)=0
cos(x/2)*(2cos(x/2)+1)=0
cos(x/2)=0⇒x/2=π/2+πn⇒x=π+2πn
cos(x/2)=-1/2⇒x/2=+-2π/3+2πn⇒x=+-4π/3+4πn
2)-cos2x+5sinx+3=0
2sin²x-1+5sinx+3=0
2sin²x+5sinx+2=0
sinx=a
2a²+5a+2=0
D=25-16=9
a1=(-5-3)/4=-2⇒sinx=-2 нет решения
a2=(-5+3)/4=-1/2⇒sinx=-1/2⇒x=(-1)^n+1*π/6+πn