A ray of light through (2, 1) is reflected at a point P on the y-axis and then passes through the point (5, 3). If this reflected ray is the directrix of any ellipse with eccentricity 1/3 and the distance of the nearer focus from this directrix is 8/√53, then the equation of the other directrix can be:

Option 1 - <p>2x - 7y - 39 = 0 or 2x - 7y - 7 = 0<br>&lt;!--[endif]--&gt;</p>
Option 2 - <p>11x + 7y + 8 = 0 or 11x + 7y - 15 = 0<br>&lt;!-- [if !supportLineBreakNewLine]--&gt;<br>&lt;!--[endif]--&gt;</p>
Option 3 - <p>2x - 7y + 29 = 0 or 2x - 7y - 7 = 0</p>
Option 4 - <p>11x - 7y - 8 = 0 or 11x + 7y + 15 = 0</p>
13 Views|Posted 6 months ago
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1 Answer
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6 months ago
Correct Option - 3
Detailed Solution:

Reflected point of (2,1) about y-axis is (-2,1).

Reflected ray passes through (-2,1) and (5,3).
Equation: (y-1)/ (x+2) = (3-1)/ (5+2) = 2/7 ⇒ 2x - 7y + 11 = 0.
This is one directrix. Let the other be 2x - 7y + α = 0.
Distance between directrices = 2a/e = |11-α|/√53.
Distance from focus to directrix = a/e

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Maths Ncert Solutions class 11th 2026

Maths Ncert Solutions class 11th 2026

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