Area = (angle/2π)πr^2 because the area of a sector is basically the total area (πr^2) divided by the fraction of the whole (angle/2π). 2π = the whole of the circle in radians.
So for your problem Area = (5π/2/2π)π(4^2) = (5π/4π)π(16) = (5/4)(3.14)(16) = 20(3.14) = 62.8
Hope this helps!
