How do I find the cycle interval for the following F x cos x

How do I find the cycle interval for the following?

F (x)= cos x

G (x)= cos (x+pi/2)

I think I\'m suppose to set each equation to 0 and to 2pi, but I don\'t know what to do while the cosine

Solution

In mathematics, a periodic function is a function that repeats its values in regular intervals or periods. The most important examples are the trigonometric functions, which repeat over intervals of 2 radians.

standard equation of cosine fnction is Acos(Bx+C)

it has period T=2pi/B

1) given F(x) =cosx

period T = 2pi/B = 2pi/1 = 2pi

2) G(x) = cos(x+pi/2)

period T = 2pi/1 = 2pi