Given
Major axis of length = 12
Foci at ( 9 ,1 ) and ( -1, 1 )
Find
Equation of an ellipse
Explanation
As we know , major axis = 2a = 12
thus a = 6
the midpoint between the foci is the center , so
[tex]\begin{gathered} C:(\frac{8}{2},\frac{2}{2}) \\ C:(4,2) \end{gathered}[/tex]
the distance between the foci is equal to 2c
[tex]\begin{gathered} 2c=\sqrt{\left(9+1\right)^2+0^2} \\ 2c=10 \\ c=5 \end{gathered}[/tex]
now,
[tex]\begin{gathered} c^2=a^2-b^2 \\ b^2=a^2-c^2 \\ b^2=36-25 \\ b^2=11 \end{gathered}[/tex]
so , the equation of an ellipse is
[tex]\begin{gathered} \frac{(x-h)^2}{b^2}+\frac{(y-k)^2}{a^2} \\ \frac{(x-4)^2}{11}+\frac{(y-2)^2}{36} \end{gathered}[/tex]
Final Answer
The equation of an ellipse
[tex]\frac{(x-4)^{2}}{11}+\frac{(y-2)^{2}}{36}[/tex]
