`" In a triangle "ABC" ,if "2cos A=sin B" cosec "C" then "`

In a triangle ABC, if cos A cos B+sin A sin B sin C=1, then a:b:c is equal to

In a triangle ABC, if cos A=(sin B)/(2sin C), show that the triangle is isosceles.

In a triangle ABC,sin A-cos B=cos C then angle B is

In a triangle ABC, if sin A sin(B-C)=sinC sin(A-B) , then prove that cos 2A,cos2B and cos 2C are in AP.

Statement I If in a triangle ABC sin ^(2) A+sin ^(2)B+sin ^(2)C=2, then one of the angle must be 90^(@). Statement II In any triangles ABC cos 2A+ cos 2B+cos 2C=-1-4 cos A cos B cos C