(a) We know that

is a periodic square wave of period .

With as shown in the figure.

Figure (a)

We calculate as follows: (FT of a periodic signal)

where,

Considering any one period , (say from 0 to ) and

Substituting 

which can never be 0.

Thus, is an impulse train situated at intervals of .

And has a maximum value of .

(Maximum value of T without aliasing).

(b) We know that

is a periodic square wave of period .

With as shown in the figure.

Figure (b)

We calculate as follows: (FT of a periodic signal)

where

Considering any one period , (say from 0 to T) and

Substituting 

for (i.e. k is even )

Thus, is an impulse train situated at intervals of .

And has a maximum value of .

(Maximum value of T without aliasing).