Should clarify that this is against the opponent hit with the successful attack. I assume that is the intent?
By "disarm" do you mean the optional Disarm attack from the DMG? Clarify.
Not clear what you mean by "trip". Do you mean the Shove attack? Not really clear how this is meant to work with the whip, as you make a Strength(Athletics) check to Shove.
Given that a whip is a Finesse weapon this is probably the case anyway --- depending on what is meant by a Trip and Disarm attack.
I assume that this is because you want to be able to take a tool proficiency in Whip? Is that the only reason?
I would just have the Feat give weapon proficiency in Whip instead.
While using a whip you make attempt a trip or disarm attempt as a bonus action when you successfully hit with an attack. Your answer is here already
And by trip I mean knock prone. By disarm I mean drop their weapon.