( а-4)(а-4-2а) ( от 2а-8 выносим 2)
(а-4)(-а-4)= - ( а-4)(а+4)= - ( а^2-16)= - а^2+16
1-sin²(x/2-3π)-cos²(x/4)+sin²(x/4)=(1-sin²(x/2-3π))-(cos²(x/4)-sin²(x/4))=
=cos²(x/2-3π)-cos(2*(x/4))=(cos(3π-x/2))²-cos(x/2)=(-cos(x/2))²-cos(x/2)=cos²(x/2)-cos(x/2)
26sin(π/2+α)=26cosπ/2= 26*0=0