Lagrange Error Bound Practice Test

For $f(x)=\cos x$, use $P_2(x)=1-\frac{x^2}{2}$ about $0$; if $|f^{(3)}(x)|\le 1$ on $0,0.4$, what maximum error at $x=0.4$?

Using $P_1$ for $q$ about $x=3$ to approximate $q(2.5)$, and $|q''(x)|\le 8$ on $2.5,3$, maximum error?