With a programmable calculator (or a computer), it is possible to evaluate the expressions for the sums of areas of approximating rectangles, even for large values of n, using looping. (On a TI u Is > command or a For-End For loop, on a Casio use Isz, on an HP or in BASIC use a FOR-NEXT loop.) Compute the sum of the areas of approximating rectangles using equal subintervals and righ endpoints for n 10, 30, 50, and 100. = the region under y = 4 cos(x), the x-axis, and the lines x = 0 and x = 2 n Sum of Areas 10 30 30 50 50 100 Use these estimates to guess the value of the exact area.