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Question: Answered & Verified by Expert
If y=m1x+c1 and y=m2x+c2, m1m2 are two common tangents of circle x2+y2=2 and parabola y2=x, then the value of 8 m1 m2 is equal to
MathematicsParabolaJEE MainJEE Main 2022 (25 Jun Shift 1)
Options:
  • A 32-4
  • B 62-4
  • C -5+62
  • D 3+42
Solution:
1003 Upvotes Verified Answer
The correct answer is: 32-4

Equation of the tangent to the parabola can be written as y=mx+14m or y-mx-14m=0

Now, the perpendicular distance from 0,0 to the tangent is equal to the radius of the given circle, soOM=2-14m1+m2=2

216m21+m2=1  32m4+32m2-1=0

  m2=-25+2316+22×25 ignoring the negative sign as it is square function.

Now 8m1m2=8m2

=-25+2316+223=32-4

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