I think the similarity may be like this

1- like we define log (a) we can define sin (a) where sin is a function like log

2- As you can find the value of log (a), similarly you can find the value of sin (a).

3- like you can find the anti logarithm similarly you can find inverse

e.g if log (a)=b then antilog(b) = a and if sin (a) = b then sin^-1 (b) = a

i hope this will help you.........