1+cosx-cosx/2=0 1+2cos^2(x/2)-1-cosx/2=0 cosx/2(cosx/2-1)=0
cosx/2=0 cosx/2=1
cosx/2=0 x/2=pi/2+pin x=pi+2pin 1-cosx-sinx/2=0 /2+cos^2x/2)=1/4
cosx/2=1 x/2=2pin x=4pin
2) 1-cosx-sinx/2=0 1-(1-2sin^2x/2)-sinx/2=0 1-1+2sin^2x/2-sinx/2=0 sinx/2(sinx/2-1)=0 sinx/2=0 x/2=pin x=2pin
sinx/2=1 x/2=pi/2+2pin x=pi+4pin
3)cos2x=1+sinx 1-2sin^2x=1+sinx 2sin^2x+sinx=0 sinx(sinx+1)=0
sinx=0 x=pim sinx+1=0 sinx=-1 x=-pi/2+2pim
4) sin^4x/2-cos^4x/2=1/4 (sin^2x/2-cos^2x/2)(sin^2x+cos^2x/2)=1/4
-(cos^2x/2-sin^2x/2)*1=1/4 -cosx=1/4 cosx=-1/4 x=arccos(-1/4)+2pin