Question

cos7xcos2x+sin7xsin2x=1/3

решите люди пожалуйста!!!!

Answer 1

cos7xcos2x + sin7xsin2x = 1/3

cos(7x-2x) = 1/3

cos5x = 1/3

5x = ±arccos(1/3) + 2πn

x = ±arccos(1/3)/5 + 2πn/5