Solution
Core Logic
Analyze region A: |z - 2| ≤ 4 represents a solid disk with center (2, 0) and radius R=4. Its rightmost point on the real axis is (6, 0) and leftmost is (-2, 0).
Analyze locus B: |z - 2| + |z + 2| = 5 represents an ellipse with foci at (2, 0) and (-2, 0), and major axis length 2a = 5 ⇒ a = (5)/(2). The equation of the ellipse is (x²)/((5/2)²) + (y²)/(b²) = 1. Its leftmost vertex is at (-(5)/(2), 0).
Execution
To maximize |z₁ - z₂|, we need the maximum geometric distance between any point in the disk A and any point on the ellipse B. By visualizing the placement on the coordinate plane: The rightmost point of the circle A is z₁ = 6. The leftmost point of the ellipse B is z₂ = -(5)/(2). The distance between them is the maximum horizontal span since both shapes are symmetric around the real axis and their extremes occur on the real axis.
|z₁ - z₂| = 6 - (-(5)/(2)) = 6 + (5)/(2) = (17)/(2)Pattern Recognition
Maximum distance problems between loci in the complex plane almost always resolve to finding the extreme diametric points along their shared axis of symmetry (usually the real axis).
Chapter Mix
Class 11 Maths: Complex Numbers and Quadratic Equations Class 11 Maths: Conic Sections