Which of the following sets are equal ?
`A={x:x inN,xlt3},B={1,2},C={3,1}`,
`D={x:x inN, x` is odd `xlt5}` ,
E={1,2},F={1,3}.

Answer

To determine which of the given sets are equal, we will analyze each set step by step.

### Step 1: Identify the Elements of Each Set

1. **Set A**:
- Given in set-builder form: \( A = \{ x : x \in \mathbb{N}, x < 3 \} \)
- The natural numbers less than 3 are 1 and 2.
- Thus, \( A = \{ 1, 2 \} \)

2. **Set B**:
- Given in roster form: \( B = \{ 1, 2 \} \)

3. **Set C**:
- Given in roster form: \( C = \{ 3, 1 \} \)

4. **Set D**:
- Given in set-builder form: \( D = \{ x : x \in \mathbb{N}, x \text{ is odd and } x < 5 \} \)
- The odd natural numbers less than 5 are 1 and 3.
- Thus, \( D = \{ 1, 3 \} \)

5. **Set E**:
- Given in roster form: \( E = \{ 1, 2 \} \)

6. **Set F**:
- Given in roster form: \( F = \{ 1, 3 \} \)

### Step 2: Compare the Sets

Now we will compare the sets to see which ones are equal.

- **Comparing A and B**:
- \( A = \{ 1, 2 \} \)
- \( B = \{ 1, 2 \} \)
- Both sets have the same elements. Therefore, \( A = B \).

- **Comparing A and C**:
- \( A = \{ 1, 2 \} \)
- \( C = \{ 3, 1 \} \)
- The elements do not match. Therefore, \( A \neq C \).

- **Comparing B and C**:
- \( B = \{ 1, 2 \} \)
- \( C = \{ 3, 1 \} \)
- The elements do not match. Therefore, \( B \neq C \).

- **Comparing C and D**:
- \( C = \{ 3, 1 \} \)
- \( D = \{ 1, 3 \} \)
- Both sets have the same elements (order does not matter in sets). Therefore, \( C = D \).

- **Comparing D and F**:
- \( D = \{ 1, 3 \} \)
- \( F = \{ 1, 3 \} \)
- Both sets have the same elements. Therefore, \( D = F \).

- **Comparing E and F**:
- \( E = \{ 1, 2 \} \)
- \( F = \{ 1, 3 \} \)
- The elements do not match. Therefore, \( E \neq F \).

### Step 3: Conclusion

From the comparisons, we find the following equal sets:
- \( A = B = E \)
- \( C = D = F \)

### Final Answer

The equal sets are:
1. \( A = B = E \)
2. \( C = D = F \)