When creating a left-endpoint Rie.. .ann sum on the interval [90.6, 391.4] using 40 rectangles, the 7th endpoint used t calculate the height of the approximationg rectangle would be a. 391.4 O b. 45.12 O c. 135.72 O d. 143.24 O e. 90.6When approximationg the area under the curve f(), a given left-endpoint Riemann sum on the interval [a, b], the height of the first rectangle is determined using -a+Ax and the function f(x). Select one: O True O False3 Suppose that for each i such that 1