1. anonymous

$\lim_{h \rightarrow o} \cos((\pi/2)+h)/h$ is...?

2. anonymous

$\lim_{h \rightarrow 0}\frac{\cos(\pi/2+h)-\cos(\pi/2)}{h}=(\cos(x))'$ at x = pi/2 which is -sin(pi/2) = -1

3. anonymous

you can apply the definition of a derivative or just use L'hopital rule

4. anonymous

thank you!!!