Нужен только 18 и 24, заранее благодарен

18 sin12x=1/2*sinx-√3/2*cosx sin12x=sin(x-π/3) sin12x-sin(x-π/3)=0 2sin(11x/2+π/6)cos(13x/2-π/6)=0 sin(11x+π/6)=0⇒11x/2+π/6=πn⇒11x/2=-π/6+πn⇒x=-π/33+2πn/11,n∈z cos(13x/2-π/6)=0⇒13x/2-π/6=π/2+πk⇒13x/2=2π/3+πk⇒ x=4π/39+2πk/13,k∈z 24 2cos²(x/2)-1+4cos(x/2)-5=0 cos(x/2)=a 2a²+4a-6=0 a²+2a-3=0 a1+a2=-2 U a1*a2=-3 a1=-3⇒cos(x/2)=-3<-1 нет решения a2=1⇒cos(x/2)=1⇒x/2=2πn⇒x=4πn,n∈z