A circle with radius 10 has a sector with a central angle of 2/5pi radians. What is the area of the sector?
Total area = pi r^2 = 100pi
2/(5 pi) is a fraction of 2pi
2/(5pi) / 2pi * pi * 10^2 = 6.366 units ^2
maybe that is 2/5 * pi
then 2/5 * pi / 2pi x pi x 100 = 62.83 units^2