If A = 30°, then $\dfrac{\text{sin 2 A}}{\text{1 - cos 2 A}}$ is equal to :

1. cot A

2. tan A

3. sec A

4. cosec A

$\dfrac{\text{sin 2 A}}{\text{1 - cos 2 A}}\\[1em] = \dfrac{\text{sin (2 x 30°)}}{\text{1 - cos (2 x 30°)}}\\[1em] = \dfrac{\text{sin 60°}}{\text{1 - cos 60°}}\\[1em] = \dfrac{\dfrac{\sqrt3}{2}}{1 - \dfrac{1}{2}}\\[1em] = \dfrac{\dfrac{\sqrt3}{2}}{\dfrac{2}{2} - \dfrac{1}{2}}\\[1em] = \dfrac{\dfrac{\sqrt3}{2}}{\dfrac{2 - 1}{2}}\\[1em] = \dfrac{\dfrac{\sqrt3}{2}}{\dfrac{1}{2}}\\[1em] = \dfrac{\dfrac{\sqrt3}{\cancel{2}}}{\dfrac{1}{\cancel{2}}}\\[1em] = \dfrac{\sqrt3}{1}\\[1em] = \text {cot A}$

Hence, option 1 is the correct option.