The given equation \( x^2 + y^2 = 4 \) represents a circle centered at the origin with radius 2.
Applying the transformation:
- First, rotation does not affect the equation structurally.
- Then, shifting the origin to (2, -2) results in replacing \( x \) and \( y \) with \( (X+2) \) and \( (Y-2) \).
Expanding:
\[
(X+2)^2 + (Y-2)^2 = 4
\]
\[
X^2 + 4X + 4 + Y^2 - 4Y + 4 = 4
\]
\[
X^2 + Y^2 + 4X - 4Y + 4 = 4
\]
\[
X^2 + Y^2 + 4X - 4Y + 0 = 0
\]
Thus, \( a = 4 \), \( b = -4 \), \( c = 0 \), and \( a + b + c = 0 \).