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TS EAMCET · Maths · Parabola

\(P\) and \(Q\) are the extremities of a focal chord of the parabola \(y^2=4 a x\). If \(P=(9,9)\) and \(Q=(p, q)\), then \(p-q=\)

  1. A \(-\frac{27}{16}\)
  2. B \(\frac{63}{16}\)
  3. C \(\frac{45}{16}\)
  4. D \(\frac{81}{16}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{45}{16}\)

Step-by-step Solution

Detailed explanation

\(y^2=4 a x, P\) lies on parabola \(\therefore 81=4 \times a \times 9 \Rightarrow a=\frac{9}{4}\) We know extremities of focal chord are \(P\left(a t^2, 2 a t\right)\) and \(Q\left(\frac{a}{t^2}, \frac{-2 a}{t}\right)\) Comparing,…