I'm having a discussion (read: argument) with my calculus teacher about this.

I say that if you evaluate this limit it turns out undefined. She says that since the expression results in division by zero, l'Hopital's rule can be used.Code:lim cos(x) - .5 --------- h->PI/6 PI/6 - x

and this results in 0.5Code:lim sin(x) --------- h->PI/6 1

Who is right? I think I am, but I want a general concensus here so I don't keep fighting a losing battle here.