a)

The frequency variable f can be defined by

For every fixed value of the frequency ‘F’.
is periodic indeed. It can be represented.


It is the fundamental period of sinusoidal signal


So it is period with that period.
b)

The frequency variable f can be defined by



So, it is non periodic.
c)

The frequency variable ‘f’ can be defined by



So, it is non periodic. Because the frequency is not expressed in the ratio of two integers.
d)

In this the frequency variable
can be defined by










So, the product of the 
It is non – periodic.
e)

In this the frequency variable
,
,
can be defined by
,
, 


So,
so,
so, 
So, the
is period.
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