1.
Let A={θ∈(−π2,π):3+2isin⁡θ1−2isin⁡θ is purely imaginary}A = \left\{\theta \in \left(-\dfrac{\pi}{2}, \pi\right) : \dfrac{3 + 2i\sin\theta}{1 - 2i\sin\theta} \text{ is purely imaginary}\right\}. Then the sum of the elements in AA is: