Question

упростите выражение
cos5a*sin4a-sin5a*cos4a+sina

Answer 1

cos5a*sin4a-sin5a*cos4a+sina = sin(4a-5a) + sin(a) = sin(-a) + sin(a) = -sin(a)+sin(a) = 0
Ответ: 0.

Answer 2

sina*cosb-cosa*sinb=sin(a-b)
sin4acos5a-sin5acos4a=sina=sin(4a-5a)+sina=sin(-a)+sina=
=-sina+sina=0