NCERT Class XI Mathematics - Conic Sections - Solutions
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Question : 34
Total: 71
Solution:
Given equation of ellipse is 36 x 2 + 4 y 2 = 144
i.e.,
+
= 1 ⇒
+
= 1
Clearly, 36 > 4
The equation of ellipse in standard form is
+
= 1
∴a 2 = 36 ⇒ a = 6 and b 2 = 4 ⇒ b = 2
We know that c =√ a 2 − b 2 ⇒ c = √ 36 − 4 = √ 32 = 4 √ 2
∴ Coordinates of foci are (0, ± c)
i.e. (0, ± 4√ 2 )
Coordinates of vertices are (0, ± a) i.e. (0, ± 6).
Length of major axis = 2a = 2 × 6 = 12
Length of minor axis = 2b = 2 × 2 = 4
Eccentricity (e) =
=
=
Length of latus rectum =
=
=
i.e.,
Clearly, 36 > 4
The equation of ellipse in standard form is
∴
We know that c =
∴ Coordinates of foci are (0, ± c)
i.e. (0, ± 4
Coordinates of vertices are (0, ± a) i.e. (0, ± 6).
Length of major axis = 2a = 2 × 6 = 12
Length of minor axis = 2b = 2 × 2 = 4
Eccentricity (e) =
Length of latus rectum =
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