Question

sen 90 - sen 150 / cos 120

Answer 1

Se de fato for sen90° - sen150°/cos120, fica:
1 - sen(180°-150°)/ {-cos(180°-120°)] = 1 - sen30°/(-cos60°) =
1 - 1/2/(-1/2) = 1 + 1 = 2

Mas me parece que deve ser: (sen90° - sen150°)/cos 120° =
(1 - 1/2)/(-1/2) = (1/2)/(-1/2) = -1