I am trying to solve an equation in the book Digital Image Processing, but I am stuck in the steps in between the formula and solution. Here's the equation, the last line is the solution.
Sorry it's in image format since I was having difficulty with the equation writing here.
Starting from: $-\frac{T}{j2\pi ua}(e^{-j2\pi ua}-1)=-\frac{T}{j2\pi ua}(e^{-j2\pi ua}-e^{-j\pi ua}e^{j\pi ua})=-\frac{T}{j2\pi ua}(e^{-j\pi ua}-e^{j\pi ua})e^{-j\pi ua}=\frac{T}{j2\pi ua}(-e^{-j\pi ua}+e^{j\pi ua})e^{-j\pi ua}=\frac{T}{\pi ua}sin(\pi ua)e^{-j\pi ua}$