discovered attack
You mean Queen's Gambit.
The first example was kinda stupid, if I may say that. Sure it shows the idea, but it's still a pretty bad blunder.
Well black can win the rook with Queen check... sure he loses the knight, but Queen vs. Bishop is pretty bad for white
right...that was just to demonstrate. White can win the knight with 1. Rh4+, but I wasn't getting into double attacks yet.
Remember that discovered check is when a piece moves out of the way of another piece that gives check? A discovered attack is like that, except it's just an attack on a normal piece (not the king) . For example: