[i_no_can_eat]

> with the exception of knowing that the first term of the sine and tangent expansions when the argument is in radians is just X.

There are more terms in the expansion that you can use, that's the whole point of using an expansion...

> Solving physics problems using the expansion of an unknown function in the Taylor series has nothing to do with knowing which is the Taylor series of the sine function.

I hope you're aware that the sine function appears quite often in Physics problems.