$e^{\log _{10} \tan 1^{\circ}+\log _{10} \tan 2^{\circ}+\log _{10} \tan 3^{\circ}+\ldots+\log _{10} \tan 89^{\circ}}$ ની કિંમત શોધો.

જો $\cos A+\cos (A+B)+\cos (A+2 B)+\ldots$ $n$ પદો સુધી $=$ $\cos \left(\frac{2 A+(n-1) B}{2}\right) \sin \frac{n B}{2} \operatorname{cosec} \frac{B}{2}$ હોય,તો $\cos \frac{\pi}{19}+\cos \frac{3 \pi}{19}+\cos \frac{5 \pi}{19}+\ldots+\cos \frac{17 \pi}{19} = $

$\frac{e^{4x} + e^{-4x} + 14}{4(e^x - e^{-x})^2} = \dots$

$\sqrt{3} \operatorname{cosec} 20^{\circ} - \sec 20^{\circ}$ ની કિંમત શોધો.

જો $\frac{\cos x}{a} = \frac{\cos (x + \theta)}{b} = \frac{\cos (x + 2\theta)}{c} = \frac{\cos (x + 3\theta)}{d}$ હોય,તો $\left( \frac{a + c}{b + d} \right)$ ની કિંમત શોધો:

$\operatorname{sech}^2\left(\tanh ^{-1} \frac{1}{2}\right)+\operatorname{cosech}^2\left(\operatorname{coth}^{-1} 3\right)=$