In the given figure ABCD is a rhombous, if ∠ACD = 40°, then x is:

50° 40° 60° 90°

50°

In a rhombus opposite angles are equal and diagonals bisect each others at right angle. \(\angle\) ACD = \(\angle\) CAD = 40° \(\angle\) CAD = \(\angle\) CAB = 40°     [diagonal bisect the angles] In ΔABO, \(\angle\) AOB = 90° , \(\angle\) OAB = 40° Therefore,  \(\angle\) ABO = x° = 90° - 40° = 50°