Let P and Q be distinct points on the parabola y 2 = 2 x   such that a circle with P Q as diameter…

Let P and Q be distinct points on the parabola y2=2x  such that a circle with PQ as diameter passes through the vertex O of the parabola. If P lies in the first quadrant and the area of the triangle ΔOPQ is 32, then which of the following is (are) the coordinates of P?
  1. 4,22
  2. 9,32
  3. 14,12
  4. 1,2

Solution

=32

1200t122t1t222t200

12t12t22-t22t12=±32

14t1t2t1-t2=±32

t1t2t1-t2=±122

t1-t2=±32

  t1-t2=32 (as t1>t2)

t1+t2=18-16=±2

2t1=32+2

t1=22

2t1=22

t1=2

P4,22 and P1,2

Asked in: JEE Advanced 2015 (Paper 1)

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