Answer:
[tex]\bold{4\pi\ square\ miles\approx12,56\ square\ miles}[/tex]
Step-by-step explanation:
360°:4 = 90° so the area of a sector bounded by a 90° arc is a quarter of area of a circle of the same radius.
[tex]A=\frac14\pi R^2=\frac14\pi\cdot4^2=\frac14\pi\cdot16=4\pi\approx4\cdot3,14=12,56\ square\ miles[/tex]
