For n ∈ N , let S n = z ∈ C : z - 3 + 2 i = n 4 and T n = z ∈ C : z - 2 + 3 i = 1 n . Then…

For nN, let Sn=zC:z-3+2i=n4 and Tn=zC:z-2+3i=1n. Then the number of elements in the set nN:SnTn=ϕ is
  1. 0
  2. 2
  3. 3
  4. 4

Solution

Here Sn:z-3-2i=n4 represents a circle with center C13,-2 and radius n4

and Tn:z-2-3i=1n represents a circle with center C22,-3 and radius 1n

For SnTn=ϕ, both circles do not intersect each other.

When C1C2>n4+1n

i.e. 2>n4+1n
then possible values of n=1,2,3,4

When C1C2<n4-1n

2<n2-44n

then n has infinite solutions for nN

Hence, there are total four values possible.

 

Asked in: JEE Main 2022 (25 Jul Shift 1)

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