Solve the given problems.
Display the graphs of $y_{1}=\cos x$ and $y_{n}=\frac{\sin (x+h)-\sin x}{h}$ on the same screen of a calculator for $0 \leq x \leq 2 \pi .$ For $n=2,$ let $h=0.5 ;$ for $n=3,$ let $h=0.1 .$ (You might try some even smaller values of $h .$ ) What do these curves show?