Use Taylor's Theorem to approximate an upper bound for the error approximation.
Sinh$(.9) \approx .9 + \frac{(.9)^3}{3!}$.
From the formula,
$R_4(x) \leq \frac{|.9|^5}{120}$|cosh$(.9)$|. However, I'm getting the wrong answer. Am I missing something?
Any help appreciated.