USING SCHEME

+8 Write a tail-recursive function, cos, which takes a number, x, as its argument and returns cos(x). Your function should approximate cos(x) by summing the first 100 terms of the following Taylor series: x x x x cos(x) + + O! 2! 4! 6! Any helper functions you need should be defined within the body of sin using letrec. Note: There is a good way and a bad way to do this. The good way avoids computing the factorial and the power of x which appear in each term in the series from scratch each time. In other words, do not use or define fact or expt. 8