Find the value of $\cos \left(-1710^{\circ}\right)$.
We know that values of cos $x$ repeats after an interval of $2 \pi$ or $360^{\circ} .$
Therefore, $\cos \left(-1710^{\circ}\right)=\cos \left(-1710^{\circ}+5 \times 360^{\circ}\right)$
$=\cos \left(-1710^{\circ}+1800^{\circ}\right)=\cos 90^{\circ}=0$
Prove that $2 \sin ^{2}\, \frac{3 \pi}{4}+2 \cos ^{2}\, \frac{\pi}{4}+2 \sec ^{2}\, \frac{\pi}{3}=10$
If $A + B + C = \pi $ and $\cos A = \cos B\,\cos C,$ then $\tan B\,\,\tan C$ is equal to
Find the value of:
$\tan 15^{\circ}$
The value of $\frac{{\cot 54^\circ }}{{\tan 36^\circ }} + \frac{{\tan 20^\circ }}{{\cot 70^\circ }}$ is
The equation ${\sin ^2}\theta = \frac{{{x^2} + {y^2}}}{{2xy}},x,y, \ne 0$ is possible if