ExamBro
ExamBro
JEE Advanced · Mathematics · 13. Parabola

Paragraph:

Let \(a, r, s, t\) be nonzero real numbers. Let \(P\left(a t^{2}, 2 a t\right), Q, R\left(a r^{2}, 2 a r\right)\) and \(S\left(a s^{2}, 2 a s\right)\) be distinct points on the parabola \(y^{2}=4 a x\). Suppose that \(P Q\) is the focal chord and lines \(Q R\) and \(P K\) are parallel, where \(K\) is the point \((2 a, 0)\).


Question:

The value of \(r\) is

  1. A -1t 
  2. B t2+1t
  3. C 1t
  4. D t2-1t
Verified Solution

Answer & Solution

Correct Answer

(D) t2-1t

Step-by-step Solution

Detailed explanation

Slope (QR) = slope (PK)
2at-0at2-2a=-2at-2arat2-ar2 
  tt2-2=-1t+r1t2-r2     r=t2-1t
Same subject
Explore more questions on app
From JEE Advanced
Explore more questions on app