1.
Let θ=π5\theta = \dfrac{\pi}{5} and A=(cos⁡θsin⁡θ−sin⁡θcos⁡θ)A = \begin{pmatrix} \cos\theta & \sin\theta \\ -\sin\theta & \cos\theta \end{pmatrix}. If B=A+ATB = A + A^{T}, then det⁡(B)\det(B):