Корень из 2 sin 13п/8 cos 13п/8

sqrt(2sin13p/8 *cos13p/8) = sqrt(sin13p/4) = sqrt(sin 5p/4) = sqrt(sin(p/4 + p))

[latex]sqrt{2sin(frac{13pi}8)cos(frac{13pi}8)}=sqrt{sin(2*frac{13pi}8)}=sqrt{sin(frac{13pi}4)}=\\=sqrt{sin(frac{5pi}4)}=sqrt{-frac{sqrt2}2[/latex]