If a = tan θ and b = sec θ, the relation between a and b is :

1. a × b = 1

2. a² - b² = 1

3. b² - a² = 1

4. a² + b² = 1

(sec θ - cos θ)² - (sec θ + cos θ)² is equal to :

1. 4

2. 2

3. -2

4. -4

(cot A - cot B)² + (1 + cot A cot B)² is equal to :

1. sec² A - cos² A

2. sec² A - cosec² A

3. (1 + tan A)² - (1 - cot A)²

4. cosec² A . cosec² B