Step 1: Equation of the circle.
The center of the circle lies at the intersection of the two mutually perpendicular lines. To find the center, we solve the system of equations:
\[
x + (k-1)y + 3 = 0
2x + k2y - 4 = 0
\]
By solving this system, we find the coordinates of the center \( (h, k) \).
Step 2: Use the equation of the line and circle.
Next, substitute the equation of the line \( x - y + 2 = 0 \) into the circle equation to find the points of intersection A and B, and calculate \( (AB)^2 \).
Final Answer: 18