Consider the following statements in respect of two non-empty sets A and B :

1. A ∪ B = A ∩ B if A = B

2. A Δ B = ϕ  if A = B

Which of the above statements is/are correct ?

Consider the following statements in respect of the relation R in the set IN of natural numbers defined by xRy if x² - 5xy + 4y² = 0 :

1. R is reflexive

2. R is symmetric

3. R is transitive

Which of the above statements is /are correct ?

Consider the following statements in respect of any relation R on a set A :

1. If R is reflexive, then R^-1 is also reflexive

2. If R is symmetric, then R^-1 is also symmetric

3. If R is transitive, then R^-1 is also transitive

Which of the above statements are correct?

What is the principal argument of $\frac{1}{1 + i}$ where $i = \sqrt{-1}?$