I just need the answer for part b

Let f C^2[x0,x1] and P1 its interpolation linear polynomial at xo and x1. Prove that ||f - P1|| infinity LE 1/8 (x1 - x0)^2 M2, where |f''(x)| LE M2 for all x [x,x1], and ||f - P1|| infinity = max x [x0,x1] |f(x) - P1(x)|. Let P1(x) be the linear polynomial that interpolates f(x) = sin x at xO = 0 and X1 = pi/2. Using find a bound for the maximum error ||f - P1|| infinity and compare this bound with the actual error at x = pi/4