Which of the following are identically true ? For those that are not, say when they are true.

1. \(A \cup (B\cap C) = (A\cup B) \cap (A \cup C)\)
2. \(A \cap (B\cap C)= (A \cap B) \cap C\)
3. \( A \cup B) \cap C = A \cup (B\cup C) \)
4. \( A \setminus (B\cap C) = (A\setminus B) \cup (A \setminus C)\)

[GS2, p.1 # 5]