Crossword puzzle clue "kind of room on line"

Kind of room on-line

Add vertical line 13 (word 3) and vertical line 3 (word 1) together and enter the answer to the resulting clue on this line

Add vertical line 9 (word 2) and vertical line 7 (word 2) and enter the answer to the resulting clue on this line

Add vertical line 1 (word 1) and vertical line 15 (word 3) and enter the answer to the resulting clue on this line

Add vertical line 15 (word 1) and vertical line 1 (word 3) and enter the answer to the resulting clue on this line

___ Room (largest room in the White House)

Living room-dining room shape, perhaps

Actor with the line "Gentlemen, you can't fight in here! This is the War Room!"