Sin560=sin200=-sin20
sin400=sin40=2sin20cos20
cos800=cos80=sin10
sin770=sin50=cos40
-sin20/2sin20cos20sin10cos40=-1/2cos20sin10cos40=-1:1/4=-4
2cos20cos40sin10=2*1/2sin10(cos20+cos60)=sin10(cos20+1/2)=
=sin10cos20+1/2*sin10=1/2sin(-10)+1/2sin30+1/2sin10=1/2*1/2=1/4