Ellipse
Major and Minor Axes
Grade 11
Question:
<p>Let an ellipse having major axis and minor axis parallel to x-axis and y-axis respectively. Its two foci <span>S</span> and <span>S'</span> are <span>(2, 1)</span>, <span>(4, 1)</span> and a line <span>x + y = 9</span> is a tangent to this ellipse at point <span>P</span>. Find the length of major axis.</p>
<p>(a) <span>√13</span></p>
<p>(b) <span>2√11</span></p>
<p>(c) <span>2√13</span></p>
<p>(d) <span>4√3</span></p>
Step-by-Step Solution
Key Concept: Use the focal property of ellipse and the tangent condition to establish an equation for the semi-major axis <span>a</span>.
<p>Answer: (c)</p>
Correct Answer: C