Question

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

Answer 1

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

=0,25

Answer 2

Благодарю!!!