Question:

Let $z=x+iy$ be a complex number, where $i=\sqrt{-1}$ is the complex unit. Then $|z-1+i|=5$ is a circle with:

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Always factor out a negative sign to identify the centre $z_0$ correctly.
Updated On: Apr 28, 2026
  • centre at (-1,1) and radius 5
  • centre at (1,1) and radius $\sqrt{5}$
  • centre at (-1,-1) and radius $\sqrt{5}$
  • centre at (1,1) and radius 25
  • centre at (1,-1) and radius 5
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The Correct Option is

Solution and Explanation

Step 1: Concept
The equation $|z - z_0| = r$ represents a circle with centre $z_0$ and radius $r$.

Step 2: Analysis

Rewrite $|z - 1 + i| = 5$ as $|z - (1 - i)| = 5$.

Step 3: Conclusion

The centre is $z_0 = 1 - i$, which corresponds to the point $(1, -1)$, and the radius is 5. Final Answer: (E)
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