Welcome to Westonci.ca, where curiosity meets expertise. Ask any question and receive fast, accurate answers from our knowledgeable community. Join our platform to connect with experts ready to provide accurate answers to your questions in various fields. Get immediate and reliable solutions to your questions from a community of experienced professionals on our platform.

Find the equation of the ellipse that has its foci at (2,1) and (2,-7) and b= 2

Sagot :

Foci: (2,1) and (2,-7)

[tex]F_1=\text{ (0+ x', 0 + y')}[/tex]

The center of the ellipse is 2, 3

[tex]\begin{gathered} F_1=\text{ (0+ 2, 1 + 3)}=>F_1(0,4) \\ F_2=(0+2,-7+3)\Rightarrow F_2(0,-4) \\ \text{Hence, c=4} \end{gathered}[/tex]

[tex]F_2=\text{ (0+x', 0 + y')}[/tex]

From

[tex]\begin{gathered} c^2=a^2-b^2 \\ a^2=c^2+b^2 \\ c=4,\text{ b=2} \\ a^2=4^2+2^2=16+4=20 \\ a^2=20 \end{gathered}[/tex]

The general equation of an ellipse with center ( x' ,y')

where, x'=2 and y' =3

[tex]\frac{(x-x^{\prime})^2}{b^2}+\frac{(y-y^{\prime})^2}{a^2}=1[/tex][tex]\begin{gathered} \frac{(x-2)^2}{4}+\frac{(y-3)^2}{20}=1 \\ \frac{5(x-2)^2+(y-3)^2}{20}=1 \end{gathered}[/tex][tex]\begin{gathered} 5(x-2)^2+(y-3)^2=20 \\ 5(x^2-4x+4)+(y^2-6y+9)=20 \\ 5x^2-20x+20+y^2-6y+9=20 \\ 5x^2+y^2-20x-6y+29-20=0 \\ 5x^2+y^2-20x-6y+9=0 \end{gathered}[/tex]

Hence the equation of the ellipse is

[tex]5x^2+y^2-20x-6y+9=0[/tex]