Noppi is a great app for learning notes on a music sheet. It is also possible to answer by trombone slide position.
Noppi - note practice program for instruments - is a simple program to practice notes, what a note is called when seeing it on a music sheet and what position to put the trombone slide at to create the correct tone!
Now you can also practice what notes are in a chord!
Please email me at firstname.lastname@example.org for suggestions, requests and feedback (for instance, do you want more chords, and in that case which?)
This app works offline and is open source. The source code can be found at https://github.com/SlimSim/Noppi/