$\text{ The square of diameter of the circle having tangent at }(1,1)\text{ as }x+y-2=0\text{ and passing through (2, 2) is …… }$

$\text{ Given equation of tangent at }P(1,1)\text{ is }x+y-2=0$

$\text{ Then, normal equation at }P\text{ is }x-y=0$

$\Rightarrow \text{ Diameter will be }x-y=0$

$\text{ And }Q(2,2)\text{ lies on }x-y=0$

$\Rightarrow \text{ It is other end of diameter }$

$\therefore \text{ Length of diameter }=PQ=\sqrt{1+1}=\sqrt{2}$

 Square of the length of the diameter = 2

 Therefore, the correct answer is 2.00