Question

find the limit
limit as x approaches pi/3 of [f(x)-f(pi/3)]/[x-pi/3]
f(x) = sin (x)

Answer 1

are you allowed L'Hospital, it makes it easy to solve

Answer 2

f'(pi/3) is ......
f'(x)=cos(x)
f'(pi/3)=cos(pi/3)