Question:

If the distance of a point P on an ellipse from its focus (1, 2) is half of the distance of P from its corresponding directrix \( x+y=0 \), then the point of intersection of the given directrix and its major axis, is

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The eccentricity value (\( e = 1/2 \)) given in the text is extra data. The axis direction depends entirely on the orientation of the directrix line and the position of the focus point.
Updated On: Jun 8, 2026
  • \( (2,-2) \)
  • \( (-\frac{1}{2},\frac{1}{2}) \)
  • \( (-1,1) \)
  • \( (\frac{1}{3},-\frac{1}{3}) \)
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The Correct Option is B

Solution and Explanation

Concept: By definition, the major axis of an ellipse is a line that passes through its focus and is strictly perpendicular to its directrix line. The intersection point can be found by writing the equation of the major axis line and solving it simultaneously with the directrix equation.

Step 1: Finding the slope of the major axis.
The given directrix line is: \[ x + y = 0 \implies y = -x \] The slope of the directrix is \( m_1 = -1 \). Since the major axis is perpendicular to the directrix, its slope \( m_2 \) must satisfy: \[ m_2 \times (-1) = -1 \implies m_2 = 1 \]

Step 2: Formulating the equation of the major axis.
The major axis passes through the focus point \( (1, 2) \) with a slope of 1: \[ y - 2 = 1(x - 1) \implies y - 2 = x - 1 \implies x - y + 1 = 0 \]

Step 3: Finding the intersection point.
We solve the system of linear equations: 1) \( x + y = 0 \implies y = -x \)
2) \( x - y + 1 = 0 \)
Substitute (1) into (2): \[ x - (-x) + 1 = 0 \implies 2x + 1 = 0 \implies x = -\frac{1}{2} \] This gives \( y = -(-\frac{1}{2}) = \frac{1}{2} \). Thus, the intersection point is \( \left(-\frac{1}{2}, \frac{1}{2}\right) \). This tracks Option (B).
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