cos A+cos B+cos C+cos D=0

(cos(A+B))/(cos(A-B))+(cos(C-D))/(cos(C+D))=0rArr cot A cot B cot C cot D=

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=0, then the value of sin^(2)A+cos C(cos A cos B-cos C)+cos B(cos A cos C-cos B) is equal to: -1 (b) 0(c)1 (d) none of these

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

A,B,C,D are the angles of a cyclic quardrilateral ABCD , what is the value of cos A+cos B + cos C + cos D ?

If three angles A, B, C are such that cos A+ cos B + cos C = 0 and if lambda cos A cos B cos C = cos 3A + cos 3B + cos 3C , then value of lambda is :

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0