Consider the following statements 

1. A = (A ∪ B) ∪ (A - B),

2. A ∪ (B - A) = (A ∪ B)

3. B = (A ∪ B) - (A - B)

Which of the statements given above are correct?

A function satisfies $f(x-y)=\frac{f(x)}{f(y)}$, where f(y) ≠ 0. If f(1) = 0.5, then what is f(2) + f(3) + f(4) + f(5) + f(6) equal to ?

What is 2 cot $\left(\frac{1}{2} \cos ^{-1} \frac{\sqrt{5}}{3}\right)$ equal to ?

If sec-1 p - cosec-1q = 0, where p > 0, q > 0; then what is the value of p-2 + q-2 ?