Use the upper and lower sums to approximate the area of the region using the given number of subintervals (of equal width)
y=sqrt(1-x^2)
https://www.webassign.net/larson/4_02-30.gif
I was able to find the upper sum, which was 0.895, but I cannot find the lower sum. I have gotten 0.824 and 0.659 as answers, but neither are considered correct.