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Question: Answered & Verified by Expert
Consider the circles
S1: x2+y2+2x+8y-23=0 and S2: x2+y2-4x+10y+19=0
If the polars of the centre of a circle with respect to the another circle are L1 and L2, then L1, L2 are
MathematicsCircleTS EAMCETTS EAMCET 2020 (09 Sep Shift 1)
Options:
  • A parallel and separated by a distance of 410 units
  • B perpendicular and intersect at 1,3
  • C perpendicular and intersect at 1,-5
  • D parallel and separated by a distance of 210 units
Solution:
1565 Upvotes Verified Answer
The correct answer is: parallel and separated by a distance of 410 units

We have 

S1: x2+y2+2x+8y-23=0  c1-1, -4 and S2: x2+y2-4x+10y+19=0 c22, -5

Given that the polars of the centre of a circle with respect to another circle are L1 and L2

We know that equation of polar is given by T=0

Now L1: -x-4y-2x-1+5y-4+19=0

L1: -3x+y+1=0

L2: 2x-5y+x+2+4y-5-23=0

L2: -3x+y+41=0

Clearly L1  L2

Distance between them is =41-19+1=4010=410 units.

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