Set Theory 79278F
1. **Problem:** Given sets $U$, $A$, and $B$ where $A$ and $B$ are subsets of $U$, determine which of the following statements are true:
i. $A \cup B = A \cap B$
ii. $A \cup A = U$
iii. $A \cap \emptyset = \emptyset$
2. **Formula and Rules:**
- The union of two sets $A$ and $B$, $A \cup B$, contains all elements in $A$ or $B$ or both.
- The intersection of two sets $A$ and $B$, $A \cap B$, contains only elements common to both $A$ and $B$.
- The empty set $\emptyset$ has no elements.
3. **Evaluate each statement:**
- i. $A \cup B = A \cap B$ is generally false because union includes all elements from both sets, intersection only common elements.
- ii. $A \cup A = A$, not necessarily $U$, so this is false.
- iii. $A \cap \emptyset = \emptyset$ is true because intersection with empty set is empty.
4. **Conclusion:** Only statement iii is true.
5. **Answer:** None of the options exactly match only iii, so the correct choice is (গ) ii ও iii is false because ii is false, (খ) i ও iii is false because i is false, (ক) i ও ii is false, (ঘ) i, ii ও iii is false. So only iii is true, but no option matches only iii. Hence, the correct answer is none of the above.
Final answer: Only statement iii is correct.