hi,

using sin(θ)/θ x->0 = 1 explain how

a.) lim (sin2x)/5x = 2/5 as x ->0

b.)lim (cos h -1)/h = 0 as h->0 using the half angle formula cos h = 1 - 2 sin^ * (h/2)

since a. is an identity do does the substitution rule apply?

in b. i can set it up:

lim -((2sin^2 )*(h/2)/h)

im not sure what to do or how to solve this limit. my algebra is a little weak so can you explain it to me in simple terms?? any response would be great!