Chapter 2.1, Problem 27E

For the following exercises, consider the function $f(x)=\sqrt{1-x^2}$ . (Hint: This is the upper half of the circle of radius 1 positioned at (0,0).)
27. Use the preceding exercise to find the exact area between the x-axis and the graph of f over the interval [-1, 1] using rectangles. For the rectangles, use squares 0.4 by 0.4 units, and approximate both above and below the lines. Use geometry to find the exact answer.