" If "A,B,C,D" are angles of a quadrilateral then "cos A+cos B+cos C+cos D=

I: If A,B,C,D are angles of a cyclic quadrilateral then cos A + cos B + cos C + cos D=0 II : If A,B,C,D are the angles of a quadrilateral then cos""(A+B)/(2) + cos""(C+D)/(2) =0

If A,B,C,D are the angles of a cyclic quadrilateral then cos A + cos B+ cos C + cos D=

If A,B,C,D are angles of a cyclic quadrilateral,prove that cos A+cos B+cos C+cos D=0

MA.B.C.D are the angles of a cyclic quadrilateral then cos 'fr cos B+cos C-cos D=

If A,B,C,D are the angles of a cyclic quadrilateral and cos A+cos B= K(cos C + cos D), then the value of K is

If A ,\ B ,\ C ,\ D are angles of a cyclic quadrilateral, prove that cos A+cos B+cos C+cos D=0.

If A,B,C,D are angles of a cyclic quadrilateral,then prove that cos A+cos B+cos C+cos D=0

If A,B,C,D are the angles of a quadrilateral then cos""((A+B)/(2))+ cos ""((C+D)/(2)) =

In a quadrilateral ABCD,cos A cos B+sin C sin D=