\(|z-3i|\leq 1\\ \text{describes a disk centered at }(0,3i) \text{ of radius }1\\ 0\leq \arg(z-3i)\leq \dfrac \pi 2\\ \text{says to only consider the first quadrant of that circle}\\ \text{The full circle will have area }\pi (1)^2 = \pi\\ \text{The first quadrant of this circle will have area }\dfrac \pi 4\)
.\(|z-3i|\leq 1\\ \text{describes a disk centered at }(0,3i) \text{ of radius }1\\ 0\leq \arg(z-3i)\leq \dfrac \pi 2\\ \text{says to only consider the first quadrant of that circle}\\ \text{The full circle will have area }\pi (1)^2 = \pi\\ \text{The first quadrant of this circle will have area }\dfrac \pi 4\)