If sec θ = 2x and y tan θ = 2, then the value of $2\Big(x^2 - \dfrac{1}{y^2}\Big)$ is:

1. $\Big(\dfrac{1}{2}\Big)$

2. $\Big(\dfrac{1}{3}\Big)$

3. $\Big(\dfrac{1}{4}\Big)$

4. 1

(cos⁴ θ − sin⁴ θ) is equal to :

1. 2 cos² θ + 1

2. 2 cos² θ − 1

3. 2 sin² θ + 1

4. 2 sin² θ − 1

If sin θ − cos θ = 0, then the value of sin θ + cos θ is :

1. $\dfrac{1}{\sqrt{2}}$

2. $\sqrt{2}$

3. $\dfrac{1}{4}$

4. $\dfrac{3}{4}$

If sec θ + tan θ + 1 = 0, then sec θ − tan θ is equal to :

1. −1

2. 0

3. 1

4. 2