Question

Знайти інтеграли......​

Answer 1

Привет!)

$\int\limits { \frac{cos9x+cos7x}{cos8x} } \, dx =\int\limits {\frac{2cos(\frac{9x+7x}{2})cos(\frac{9x-7x}{2}) }{cos8x} } \, dx =\int\limits { \frac{2cos8xcosx}{cos8x} } \, dx =\int\limits { 2cosx} \, dx =2\int\limits {cosx } \, dx =2sinx+C$