i don't know how to prove the following limits

limit of ( 1 - cos x) / x^2 when x is +infinity

limit of (tan4x) / 6 when x is 0

limit of (sin x^2) / x

in the first equation i got to the point of multiplying by the reciprocal but i don't know what to do next

in the second equation i converted tan to sin/cos but i dont know where to go from there