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

  • A
    $2(\cos A + \cos C)$
  • B
    $2(\cos A + \cos B)$
  • C
    $2(\cos A + \cos D)$
  • D
    $0$

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