Questions in trigonometry

Select	Question
	If $\alpha +\beta +\gamma =2\pi ,$ then [IIT 1979]
	If $A+B+C=\pi ,$then $\cos \,\,2A+\cos \,\,2B+\cos \,\,2C=$
	If $A+B+C={{180}^{o}},$ then $\frac{\sin 2A+\sin 2B+\sin 2C}{\cos A+\cos B+\cos C-1}=$
	A, B, C are the angles of a triangle, then ${{\sin }^{2}}A+{{\sin }^{2}}B+{{\sin }^{2}}C-2\cos A\,\cos B\,\cos C=$
	In a triangle $\tan A+\tan B+\tan C=6$ and $\tan A\tan B=2,$then the values of $\tan A,\,\,\tan B$ and $\tan C$ are
	If $A+B+C=\pi ,$ then ${{\tan }^{2}}\frac{A}{2}+{{\tan }^{2}}\frac{B}{2}+$${{\tan }^{2}}\frac{C}{2}$ is always
	If $A+B+C={{180}^{o}},$ then $\frac{\tan A+\tan B+\tan C}{\tan A\,.\,\tan B\,.\,\tan C}=$
	If A, B, C are angles of a triangle, then $\sin 2A+\sin 2B-\sin 2C$ is equal to
	In any triangle ABC ,${{\sin }^{2}}\frac{A}{2}+{{\sin }^{2}}\frac{B}{2}+{{\sin }^{2}}\frac{C}{2}$ is equal to
	If $\cos A=\cos B\,\,\cos C$and $A+B+C=\pi ,$ then the value of $\cot \,B\,\cot \,C$ is