Hi my equation is in time domain and i want to convert it frequency domain.

My equation is 2/(1+t*t)

It can be converted by using fourier trnasform pair

The transform pair is

x(t)= e(-a|t|) X(f) = 2a/(a*a + omega square)

where omega =2*pi* frequency

or i m uploadiing similar solution having slightly different equation which i got from internet but i could not understand from where he wrote "pi". plz see it and explain me