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NCERT Class XI Mathematics - Conic Sections - Solutions

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Question : 32 of 71
Marks: +1, -0
x249+y236\frac{x^2}{49} + \frac{y^2}{36} = 1
Solution:  
Given equation of ellipse is x249+y236\frac{x^2}{49} + \frac{y^2}{36} = 1
Clearly, 49 > 36
The equation of ellipse in standard form is x2a2+y2b2\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1
a2a^2 = 49 ⇒ a = 7 and b2b^2 = 36 ⇒ b = 6
We know that c = a2c2\sqrt{a^2 - c^2} , c = 4936\sqrt{49 - 36} = 13\sqrt{13}
∴ Coordinates of foci are (±c, 0) i.e. (± 13\sqrt{13}, 0)
Coordinates of vertices are (±a, 0) i.e. (±7, 0).
Length of major axis = 2a = 2 × 7 = 14
Length of minor axis = 2b = 2 × 6 = 12
Eccentricity (e) = ca\frac{c}{a} = 137\frac{\sqrt{13}}{7}
Length of latus rectum = 2b2a\frac{2b^2}{a} = 2×367\frac{2 \times 36}{7} = 727\frac{72}{7}
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