[dore]

The second one is asking you to prove the squeeze theorem, so no you couldn't just use the squeeze theorem . But for that one you basically just have to use the definition of limits (using your greek letters ofc) on f and h and then use the fact that if g(a) > f(a) and g(a) < h(a) and f(a) = h(a) then g(a) = f(a) = h(a). It's a self-writing proof if you just write out your definitions of your givens and work them toward the destination which conclude in having the greek letter definition of limits existing for g.