Question

What is the fundamental period of 2 cos (3x)?

Answer 1

The fundamental period of `cos(theta)`
is `2pi`
That is (for example) `cos(0) " to " cos(2pi)`
represents one full period.

In the expression `2 cos(3x)`
the coefficient `2` only modifies the amplitude.

The `(3x)` in place of `(x)`
stretches the value of `x` by a factor of `3`

That is (for example)
`cos(0) " to " cos(3*((2pi)/3))`
represents one full period.

So the fundamental period of `cos(3x)` is
`(2pi)/3`

Answer 2

`(2pi)/3`

Period of cos x is `2pi`, hence period of cos 3x would be `(2pi)/3`, which means it would repeat itself 3 times between 0 and `2pi`