The expression equivalent to sec x, is :

1. $\tan x + \dfrac{\sin x}{\sec x}$

2. $\cos x + \dfrac{\tan x}{\cos x}$

3. cos x + tan x sin x

4. tan x − cos x sin x

$\dfrac{\sin^4 A − \cos^4 A}{1 − \sin^2 A}$ is equal to :

1. cot² A − 1

2. tan² A − 1

3. 1 − cot² A

4. 1 − tan² A

If cos A + cos² A = 1, then sin² A + sin⁴ A is :

1. 1

2. 2

3. 3

4. 4

$\sqrt{\Big(\dfrac{1 − \sin A}{1 + \sin A}\Big)}$ = ?

1. sec A + tan A

2. sec A − tan A

3. sec A tan A

4. none of these