Prove that limh→0[(cos(h-1))/h]=0.
Half angle formula
From an example:
limh→0[(cos(h-1))/h] = limh→0[-(2sin2(h/2))/h]
They state that they use the half-angle formula in the following way:
I'm not really sure how they are getting this from the half angle formula. Any pointer in the correct direction would be greatly appreciated. Thank you, in advance.