Cheers, in an exercise of mine I reach the point that I have to find the $F^{-1}\{Λ(ω)\}$ (where $Λ(ω)$ is the triangle function, with $1-|ω|$ for $|ω| \leq 1 $ and 0 elsewhere. Using the duality property, I know that I will have to end up with a $sinc$ function, and I also that for $x(t) = Atri(\frac{t}{T})$ we get the transform $X(ω) = F\{x(t)\} = \frac{\sin^2(πf)}{(πf)^2}$. Is there a quick way to find the result of $\frac{1}{2π}\frac{sinc^2(\frac{t}{2})}{(t/2)^2}$ without having to use the definition with the integral? Thanks