Question

Кто сможет плиз Cos5x=cos22x

Answer 1

cos5x - cos22x = 0 
- 2sin(5x -22x)/2 * sin (5x + 22x)/2 = 0 
2 sin( 17x/2) * sin (27x/2) =  0
sin( 17x/2) * sin (27x/2) =  0 

1) sin (17x/2) = 0
17x/2 = pik 
x = (2pik)/17, k ∈Z

2) sin(27x/2) = 0 
27x/2 = pik
x = (2pik)/27, k ∈Z