Question

6cos400° - 8cos³40°=​

Answer 1

Ответ:

1

Пошаговое объяснение:

6cos400° - 8cos³40°=​6cos(360°+40°) - 8cos³40° =​ 6cos40° - 8cos³40°=​​-2(4cos³40°-3cos40°)=​​-2*cos(3*40°)=-2cos120°=-2*(-1/2)=1