Нужно решить....√2sin9п/8*cos9п/8
=√2/2*2sin9π/8cos9π/8=√2/2*sin2*9π/8=√2/2*sin9π/4=√2/2*sin(2π+π/4)=√2/2*sinπ/4=√2/2*√2/2=2/4=1/2