[" 21.If "ABCD" is a cyclic quadrilateral,then "],[cos(180^(@)+A)+cos(180^(@)-B)+],[cos(180^(@)-C)-sin(90^(@)-D)=],[[" 1) "-1," 2) "0," 3) "1," 4) "2]]

If ABCD is a cyclic quadrilateral then co (180^(@) +A) + cos (180^(@) - B) +cos(180^(@)-C) - sin (90^(@) - D)=

If A,B,C,D be the angles of a cyclic quadrilateral,taken in order, prove that: cos(180^(@)-A)+cos(180^(@)+B)+cos(180^(@)+C)-sin(90^(@)+D)=0

cos A + sin(270^(@) +A)-sin(270^(@)-A)+ cos(180^(@)-A)=

If ABCD is a cyclic quadrilateral then cos A + cos B + cos C + cos D is equal to

If ABCD is a cyclic quadrilateral,then the value of cos A-cos B+cos C-cos D is

If A, B, C, D are the four angle taken in order of a cyclic quadrilateral, prove that (ii) cos (180^(@) - A) + cos (180^(@) + B) + cos (180^(@) + C) - sin (90^(@) + D) = 0

If ABCD is a cyclic quadrilateral, then the value of cos A - cos B + cos C - cos D =

If ABCD is a cyclic quadrilateral, then the value of cos^(2)A-cos^(2)B-cos^(2)C+cos^(2)D is ______.

cosA+sin(270^(@)+A)-sin(270^(@)-A)+cos(180^(@)+A)=?

If ABCD is a cyclic quadrilateral then the value of cosA+cosB+cos C+cos D is