Sin35sin84 + cos145sin6 / cos50sin21 - cos40sin111=

(sin35*sin (90-84) + cos (180-35) sin6) / (cos (90-40) sin21-cos40sin (90+21)) =

= (sin35cos6-cos35sin6) / (sin40sin21-cos40cos21) = sin (35-6) / - cos (40+21) =

=-sin29/cos61=-sin29/cos (90-29) = - sin29/sin29=-1