Period of a Periodic Function

If T is the smallest positive real number such that f(x+T) = f(s), then it is called the period f f(x)

Since


for all n Є Z ( n belongs to Z)

sin (2nπ +x) = sin x
cos (2nπ +x) = cos x
tan (nπ +x) = tan x

period of sin x = 2π
period of cos x = 2π
period of tan x = 2π