Question

Помогите с математикой!
cos10x cos5x-sin 10x sin 5x=-1​

Answer 1

Ответ:

cos10x × cos5x - sin10x × sin5x = -1

cos(10x+5x)=-1

cos(15x)=-1

15x = пи +2пи×n, n € z

x= пи/15 + 2пи/15 × n, n € z