For a project I am inputting a triangle wave into a system and what is being output is this triangle wave with a sine wave following the triangle waves input.

I would like to filter out this triangle wave and only have the sine wave signal being output. I've thought about using a band pass filter to filter out the unwanted frequencies but am afraid that this will ruin the sine wave that is being induced by the system. (From what I have looked up a band pass filter can reduce the triangle wave to a sine wave, but I would like to completely negate the triangle wave and only have the sine signal that is output from the system)

Thanks for any input.