find the equation of the ellipse in the following cases:
Vertices (± 5, 0), foci (± 4, 0)
Given that we need to find the equation of the ellipse whose vertices are (±5,0) and foci (±4,0).
Let us assume the equation of the ellipse as (a2>b2).
We know that vertices of the ellipse are (±a,0)
⇒ a = 5
⇒ a2 = 25
We know that foci = (±ae,0)
⇒ ae = 4
⇒ 5e = 4
⇒
We know that eccentricity
⇒
⇒
⇒
⇒ b2 = 9
The equation of the ellipse is
⇒
⇒
⇒ 9x2 + 25y2 = 225
∴ The equation of the ellipse is 9x2 + 25y2 = 225.