$\tan 1^{\circ} \times \tan 2^{\circ} \times \tan 3^{\circ} \times \cdots \times \tan 89^{\circ} = $

Which one of the following is possible?

If $\sin \theta = -\frac{1}{\sqrt{2}}$ and $\tan \theta = 1$,then $\theta$ lies in which quadrant?

If $\tan \theta = \frac{20}{21}$,then $\cos \theta$ will be

If $\cosh x = \frac{\sqrt{14}}{3}$,$\sinh x = \cos \theta$ and $-\pi < \theta < -\frac{\pi}{2}$,then $\sin \theta =$

If $\left[1-\cos \left(\frac{\pi}{2}+\alpha\right)+\sin \left(\frac{3 \pi}{2}+\alpha\right)\right]^2+\left[1-\sin \left(\frac{3 \pi}{2}-\alpha\right)-\cos \left(\frac{3 \pi}{2}+\alpha\right)\right]^2=a+b \sin ^2\left(\frac{\pi}{4}+\alpha\right)$,then $a^2+b^2=$