The GATE Grind

GATE 2022 MA – Question 17

Topology · Connectedness and Compactness · 1 mark · Multiple choice

In usual ℝ² let A={x²+y²≤1},B={(x−2)²+y²≤1}, M=A∪B and N=int A∪int B. Which holds?

  1. Both connected
  2. Neither connected
  3. M connected, N disconnected
  4. M disconnected, N connected

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Correct answer: (C) M connected, N disconnected

Explanation

The closed disks touch at (1,0), so their connected union M is connected. Their open interiors are disjoint, nonempty open components and separate N. Thus **C**.

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