A line y = m x + 1 intersects the circle x - 3 2 + y + 2 2 = 25 at the points P and Q . If the midpoint of…

A line y=mx+1 intersects the circle x-32+y+22=25 at the points P and Q. If the midpoint of the line segment PQ has x-coordinate -35, then which one of the following options is correct?
  1. 6m<8
  2. 2m<4
  3. 4m<6
  4. -3m<-1

Solution

Equation of line PQ:y=mx+1 Let R be the mid point of PQ, so its x-coordinate of midpoint =-35 Hence, coordinates of midpoint R-35,-3m5+1 Let centre of circle is O3,2 Since, perpendicular dropped from centre upon any chord divides it in two equal parts. Hence, line PQ will be perpendicular to RO mRQmRO=-1  m-3m5+1+2-35-3=-1 m-3m+15-18=-1 m2-5m+6=0 m=2, 3

2m<4

Asked in: JEE Advanced 2019 (Paper 1)

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