Решение 

 

 

 

 

 

Проверка 

> solve({`/`(`*`(`+`(cos(x), cos(`+`(`*`(3, `*`(x)))), cos(`+`(`*`(5, `*`(x)))))), `*`(`+`(cos(`+`(`*`(2, `*`(x)))), `/`(1, 2)))) = 0, `+`(`*`(4, `*`(y)), `*`(5, `*`(cos(`+`(`*`(3, `*`(x))))))) = 2})
 

{x = `+`(`*`(`/`(1, 3), `*`(Pi))), y = `/`(7, 4)}, {x = `+`(`*`(`/`(2, 3), `*`(Pi))), y = -`/`(3, 4)}, {x = arccos(`+`(`*`(`/`(1, 2), `*`(RootOf(`+`(`*`(`^`(_Z, 2)), `-`(3))))))), y = `/`(1, 2)}, {x =... (46.2.1)