1)sin 90градусов*sinx=2sin45 градусов*sin x/2

sin90=1; sin45=[latex] \sqrt{2}/2[/latex] sinx=[latex] \sqrt{2} [/latex]sinx/2 => 2sinx/2cosx/2-[latex] \sqrt{2} [/latex]sinx/2=0 =>  sinx/2(2cosx/2-[latex] \sqrt{2} [/latex])=0 =>  sinx/2=0 => x/2=пk => x=2пk; Cosx/=[latex] \sqrt{2} [/latex]/2 => x/2=п/4+2пk => x=п/2+4пk и x/2= -п/4+2пk => x= - п/2+4пk