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TS EAMCET · Maths · Straight Lines

Let Q be the image of a point \(\mathrm{P}(1,2)\) with respect to the line \(x+y+1=0\) and R be the image of Q with respect to the line \(x-y-1=0\). If M and N are the midpoints of PQ and QR respectively, then \(\mathrm{MN}=\)

  1. A \(\sqrt{10}\)
  2. B 4
  3. C \(\sqrt{22}\)
  4. D 5
Verified Solution

Answer & Solution

Correct Answer

(A) \(\sqrt{10}\)

Step-by-step Solution

Detailed explanation

\(P=(1,2)\) Line 1: \(x+y+1=0\) \(Q = \left(1 - 2 \frac{1(1)+1(2)+1}{1^2+1^2}, 2 - 2 \frac{1(1)+1(2)+1}{1^2+1^2}\right) = \left(1 - 2 \frac{4}{2}, 2 - 2 \frac{4}{2}\right) = (1-4, 2-4) = (-3,-2)\) Line 2: \(x-y-1=0\)…