The line x + Y-A = 0 is tangent to (x-1) square + (Y-2) square = 2, a =?

The line x + Y-A = 0 is tangent to (x-1) square + (Y-2) square = 2, a =?

Radius of center (1,2) = √ 2
Distance from center of circle to straight line = radius
|1+2-a|/√2=√2
|a-3|=2
A-3 = 2 or A-3 = - 2
A = 5 or 1