The value of $$\tan 1^{\circ} \tan 2^{\circ} \tan 3^{\circ} \ldots \tan 89^{\circ}$$ is

The value of $$\sin ^2 51^{\circ}+\sin ^2 39^{\circ}$$ is

If $$\tan A+\cot A=2$$, then the value of $$\tan ^4 A+\cot ^4 A=$$

$$\sqrt{3} \operatorname{cosec} 20^{\circ}-\sec 20^{\circ}=$$