A useful feature

I would like to see less practice and quiz problems that cover topics not yet discussed in any videos. For example, I spent a week trying to figure out how to find the value for C graph construction. Its not that complicated, in retrospect, but it isn't covered in any of the videos, either.

Now I was given the problem "What is the period of 0.25 - sin (2π (t - 2) / 28.5)

I have not seen any video that covers this. 0.25 - sin?? Its probably not that complicated either, but it would still be nice to be told how to solve it... at least once.