Geometrically, the set \(\{z \in \mathbf{C}:|z-2-2 i| \leq 1\}\) represents

Geometrically, the set \(\{z \in \mathbf{C}:|z-2-2 i| \leq 1\}\) represents
  1. a closed circular disc with center at \((-2,-2)\) and with radius 1
  2. a closed circular disc with center at \((2,2)\) and with radius 1
  3. a closed circular disc with center at \((1,1)\) and with radius 0.5
  4. a closed circular disc with center at \((-1,-1)\) and with radius 0.5

Solution

Given inequality is \(|z-2-2 i| \leq 1\) Let \(z=x+i y\), then we get \(\begin{aligned} & & \sqrt{(x-2)^2+(y-2)^2} & \leq 1 \\ \Rightarrow & & (x-2)^2+(y-2)^2 & \leq 1 \end{aligned}\) The above inequality represents a closed circular disc with center at \((2,2)\) and with radius 1. Hence, option (b) is correct.

Asked in: AP EAMCET 2020 (21 Sep Shift 1)

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