b$)$ Given a vector $x=[0\mathrm{.}1,1\mathrm{.}0,1\mathrm{.}2,0\mathrm{.}5,0\mathrm{.}8,0\mathrm{.}9]$ and a function $f(x)=sin(x),$ write a Matlab program that performs the backward difference approximation of $f^{\text{'}}(x).$ Submit both the code and the output.

$5$