Let A= 3 2isin , : is purely imaginary 2 1 2isin ì ü æ ö p +q í ý qÎ – p ç ÷ î þ è ø – q . Then the sum of the elements in A is:

Let $\mathrm{A}=\left\{\theta \in\left(-\frac{\pi}{2}, \pi\right): \frac{3+2 \mathrm{i} \sin \theta}{1-2 \mathrm{i} \sin \theta}\right.$ is purely imaginary $\}$ Then the sum of the elements in $\mathrm{A}$ is: