Question

Question 18 Find the equation for the ellipse that satisfies the given conditions: b = 3, c = 4, centre at the origin; foci on the x axis.

Class X1 - Maths -Conic Sections Page 255

Answer 1

Foci lies on X - axis hence, the equation of ellipse will be of the form x²/a² + y²/b² = 1

given, b = 3 and c = 4 .
but we know, for ellipse c² = a² - b²
4² = a² - 3²
4² + 3² = a²
a² = 25

put the values of a² = 25 and b² = 9 ( b² = 3²) in the above equation of ellipse .
hence, equation of ellipse is x²/25 + y²/9 = 1