Найдите область определения функции 1)y=1/cosx 2)y=tgx/3

Question

Найдите область определения функции 1)y=1/cosx 2)y=tgx/3

Answer 1

1
cosx≠0⇒x≠π/2+πn,n∈z
x∈(-π/2+2πn;π/2+2πn,n∈z ) U (π/2+2πn;3π/2+2πn,n∈z)
2
-π/2+πn-3π/2+3πnx∈(-3π/2+3πn;3π/2+3πn,n∈z)