Sin п/8* cos^3 п/8 - sin^3 п/8*cos п/8

$sin \frac{ \pi }{8}* cos^{3} \frac{ \pi }{8} - sin^{3} \frac{ \pi }{8}*cos \frac{ \pi }{8} =sin \frac{ \pi }{8}*cos \frac{ \pi }{8} *( cos^{2} \frac{ \pi }{8}- sin^{2} \frac{ \pi }{8} )=$
$= \frac{1}{2}*2*sin \frac{ \pi }{8} *cos \frac{ \pi }{8}*cos(2* \frac{ \pi }{8} )=$
$= \frac{1}{2}*sin(2* \frac{ \pi }{8} )*cos \frac{ \pi }{4} = \frac{1}{2}*( \frac{1}{2}*2*sin(2* \frac{ \pi }{4} ) ) = \frac{1}{4}*sin \frac{ \pi }{2} = \frac{1}{4}*1$

=0,25