12sinx=-√2sinx=-√2/2x=(-1)^(n+1)*π/4+πn,n∈z2cos(x/2+π/4)=-1x/2+π/4=π+2πnx/2=3π/4+2πnx=3π/2+4πn,n∈z31-cos²x-2cosx+2=0cosx=aa²+2a-3=0a1+a2=-2 U a1*a2=-3a1=-3⇒cosx=-3<-1 нет решенияa2=1⇒cosx=1⇒x=2⇒n,n∈z4Разделим на cos²x2tg²x+tgx-1=0tgx=a2a²+a-1=0D=1+8=9a1=(-1-3)/4=-1⇒tgx=-1⇒x=-π/4+πn,n∈za2=(-1+3)/4=0,5⇒tgx=0,5⇒x=arctg0,5+πn,n∈z52sin²x-4sinxcosx+5cos²x-2sin²x-2cos²x=03cos²x-4sinxcosx=0cosx*(3cosx-4sinx)=0cosx=0⇒x=π/2+πn,n∈z3cosx-4sinx=0/cosx3-4tgx=0tgx=3/4x=arctg0,75+πn,n∈z6sin3x-cos3x=0/cos3xtg3x-1=0tg3x=13x=π/4+πnx=π/12+πn/3,n∈zx={π/12;5π/12;3π/4;13π/12}