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Question: Answered & Verified by Expert
If the focus of a parabola divides a focal chord of the parabola into segments of lengths 5,3 units, then the length of the latusrectum of that parabola is
MathematicsParabolaAP EAMCETAP EAMCET 2019 (21 Apr Shift 1)
Options:
  • A $\frac{15}{4}$
  • B 20
  • C $\frac{25}{2}$
  • D $\frac{15}{2}$
Solution:
2830 Upvotes Verified Answer
The correct answer is: $\frac{15}{2}$
Since, semi latusrectum is the harmonic mean of segments.

So, semi laturectum length $=\frac{2 \times 5 \times 3}{5+3}=\frac{30}{8}=\frac{15}{4}$
$\therefore \quad$ Length of latusrectum $=2 \times \frac{15}{4}=\frac{15}{2}$

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