Common Core: High School - Geometry : Derive Ellipse and Hyperbola Equations: CCSS.Math.Content.HSG-GPE.A.3

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Example Questions

Example Question #1 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (9,3) and \displaystyle (-5,3) with a major axis distance of \displaystyle 10.

 

Possible Answers:

\displaystyle \frac{1}{10} \left(x - 9\right)^{2} + \frac{1}{10} \left(y - 3\right)^{2} = 1

\displaystyle \frac{1}{25} \left(x - 2\right)^{2} - \frac{1}{24} \left(y - 3\right)^{2} = 1

\displaystyle 10 x^{2} + 10 y^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{x^{2}}{10} + \frac{y^{2}}{10} = 1

Correct answer:

\displaystyle \frac{1}{25} \left(x - 2\right)^{2} - \frac{1}{24} \left(y - 3\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 9\right)^{2} = 1

\displaystyle \left ( k, h\right ) is the coordinates of the center of the foci.

\displaystyle {a} is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii is \displaystyle a.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 10

Now solve for \displaystyle a

\displaystyle a = 5.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = 2 \\y = 3.0

So the center of the foci is at \displaystyle \left ( 2, 3\right ).

Now we need to figure out what the distance from the center to the foci is \displaystyle c.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = -7

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 5.0 and \displaystyle c with -7

\displaystyle b^{2} = -24.0

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{25} \left(x - 2\right)^{2} - \frac{1}{24} \left(y - 3\right)^{2} = 1 

 

Example Question #301 : High School: Geometry

Find the equation of an ellipse that has foci at \displaystyle (7, 1) and \displaystyle (-7, 1) with a major axis distance of \displaystyle 18.

 

Possible Answers:

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{x^{2}}{18} + \frac{y^{2}}{18} = 1

\displaystyle \frac{x^{2}}{81} + \frac{1}{32} \left(y - 1\right)^{2} = 1

\displaystyle 18 x^{2} + 18 y^{2} = 1

\displaystyle \frac{1}{18} \left(x - 7\right)^{2} + \frac{1}{18} \left(y - 1\right)^{2} = 1

Correct answer:

\displaystyle \frac{x^{2}}{81} + \frac{1}{32} \left(y - 1\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 7\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii is \displaystyle a.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 18

Now solve for \displaystyle a.

\displaystyle a = 9.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = 0 \\y = 1.0

So the center of the foci is at \displaystyle \left ( 0, \quad 1\right )

Now we need to figure out what the distance from the center to the foci is \displaystyle c.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = -7

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 9.0 and \displaystyle c with -7

\displaystyle b^{2} = 32.0

Now we can substitute these values into the general equation to get.

\displaystyle \frac{x^{2}}{81} + \frac{1}{32} \left(y - 1\right)^{2} = 1 

 

Example Question #1 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (3, 4) and \displaystyle (-5, 4) with a major axis distance of \displaystyle 18.

 

Possible Answers:

\displaystyle 18 x^{2} + 18 y^{2} = 1

\displaystyle \frac{x^{2}}{18} + \frac{y^{2}}{18} = 1

\displaystyle \frac{1}{81} \left(x + 1\right)^{2} + \frac{1}{65} \left(y - 4\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{1}{18} \left(x - 3\right)^{2} + \frac{1}{18} \left(y - 4\right)^{2} = 1

Correct answer:

\displaystyle \frac{1}{81} \left(x + 1\right)^{2} + \frac{1}{65} \left(y - 4\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 3\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii \displaystyle a is.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 18

Now solve for \displaystyle a

\displaystyle a = 9.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = -1 \\y = 4.0

So the center of the foci is at \displaystyle \left ( -1, \quad 4\right )

Now we need to figure out what the distance from the center to the foci \displaystyle c is.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = -4

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 9.0 and \displaystyle c with -4

\displaystyle b^{2} = 65.0

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{81} \left(x + 1\right)^{2} + \frac{1}{65} \left(y - 4\right)^{2} = 1 

 

Example Question #302 : High School: Geometry

Find the equation of an ellipse that has foci at \displaystyle (-3, 5) and \displaystyle (-1, 5) with a major axis distance of \displaystyle 16.

 

Possible Answers:

\displaystyle 16 x^{2} + 16 y^{2} = 1

\displaystyle \frac{1}{16} \left(x + 3\right)^{2} + \frac{1}{16} \left(y - 5\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{1}{64} \left(x + 2\right)^{2} + \frac{1}{63} \left(y - 5\right)^{2} = 1

\displaystyle \frac{x^{2}}{16} + \frac{y^{2}}{16} = 1

Correct answer:

\displaystyle \frac{1}{64} \left(x + 2\right)^{2} + \frac{1}{63} \left(y - 5\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x + 3\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii \displaystyle a is.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 16

Now solve for \displaystyle a

\displaystyle a = 8.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = -2 \\ y = 5.0

So the center of the foci is at \displaystyle \left ( -2, \quad 5\right )

Now we need to figure out what the distance from the center to the foci is \displaystyle c.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate.

\displaystyle c = 1

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 8.0 and \displaystyle c with 1

\displaystyle b^{2} = 63.0

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{64} \left(x + 2\right)^{2} + \frac{1}{63} \left(y - 5\right)^{2} = 1 

 

Example Question #2 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (4, -10) and \displaystyle (-2, -10) with a major axis distance of \displaystyle 2.

 

Possible Answers:

\displaystyle \frac{1}{2} \left(x - 4\right)^{2} + \frac{1}{2} \left(y + 10\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \left(x - 1\right)^{2} - \frac{1}{8} \left(y + 10\right)^{2} = 1

\displaystyle \frac{x^{2}}{2} + \frac{y^{2}}{2} = 1

\displaystyle 2 x^{2} + 2 y^{2} = 1

Correct answer:

\displaystyle \left(x - 1\right)^{2} - \frac{1}{8} \left(y + 10\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 4\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii \displaystyle a is.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 2

Now solve for \displaystyle a

\displaystyle a = 1.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = 1 \\y = -10.0

So the center of the foci is at\displaystyle \left ( 1, \quad -10\right )

Now we need to figure out the distance from the center to the foci \displaystyle c.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = -3

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 1.0 and \displaystyle c with -3.

\displaystyle b^{2} = -8.0

Now we can substitute these values into the general equation to get.

\displaystyle \left(x - 1\right)^{2} - \frac{1}{8} \left(y + 10\right)^{2} = 1

 

 

Example Question #1 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (5, 6) and \displaystyle (10, 6) with a major axis distance of \displaystyle 18.

 

Possible Answers:

\displaystyle 18 x^{2} + 18 y^{2} = 1

\displaystyle \frac{1}{18} \left(x - 5\right)^{2} + \frac{1}{18} \left(y - 6\right)^{2} = 1

\displaystyle \frac{x^{2}}{18} + \frac{y^{2}}{18} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{1}{81} \left(x - \frac{15}{2}\right)^{2} + \frac{4}{299} \left(y - 6\right)^{2} = 1

Correct answer:

\displaystyle \frac{1}{81} \left(x - \frac{15}{2}\right)^{2} + \frac{4}{299} \left(y - 6\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 5\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii \displaystyle a is.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 18

Now solve for \displaystyle a

\displaystyle a = 9.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = \frac{15}{2} \\\\ y = 6.0

So the center of the foci is at \displaystyle \left ( \frac{15}{2}, \quad 6\right )

Now we need to figure out what the distance from the center to where the foci \displaystyle c is.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = \frac{5}{2}

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 9.0 and \displaystyle c with \displaystyle \frac{5}{2}

\displaystyle b^{2} = 74.75

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{81} \left(x - \frac{15}{2}\right)^{2} + \frac{4}{299} \left(y - 6\right)^{2} = 1 

 

Example Question #1 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (-10, -10) and \displaystyle (4, -10) with a major axis distance of \displaystyle 12.

 

Possible Answers:

\displaystyle \frac{1}{12} \left(x + 10\right)^{2} + \frac{1}{12} \left(y + 10\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle 12 x^{2} + 12 y^{2} = 1

\displaystyle \frac{x^{2}}{12} + \frac{y^{2}}{12} = 1

\displaystyle \frac{1}{36} \left(x + 3\right)^{2} - \frac{1}{13} \left(y + 10\right)^{2} = 1

Correct answer:

\displaystyle \frac{1}{36} \left(x + 3\right)^{2} - \frac{1}{13} \left(y + 10\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x + 10\right)^{2} = 1

\displaystyle \left ( k, \quad h\right )is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii \displaystyle a is.

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 12

Now solve for \displaystyle a

\displaystyle a = 6.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = -3 \\y = -10.0

So the center of the foci is at \displaystyle \left ( -3, \quad -10\right )

Now we need to figure out what the distance from the center to the foci \displaystyle c is.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = 7
Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 6.0 and \displaystyle c with 7

\displaystyle b^{2} = -13.0

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{36} \left(x + 3\right)^{2} - \frac{1}{13} \left(y + 10\right)^{2} = 1 

 

Example Question #1 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (5, -1) and \displaystyle (-6, -1) with a major axis distance of \displaystyle 14.

Possible Answers:

\displaystyle \frac{1}{14} \left(x - 5\right)^{2} + \frac{1}{14} \left(y + 1\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle \frac{1}{49} \left(x + \frac{1}{2}\right)^{2} + \frac{4}{75} \left(y + 1\right)^{2} = 1

\displaystyle 14 x^{2} + 14 y^{2} = 1

 

\displaystyle \frac{x^{2}}{14} + \frac{y^{2}}{14} = 1

Correct answer:

\displaystyle \frac{1}{49} \left(x + \frac{1}{2}\right)^{2} + \frac{4}{75} \left(y + 1\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 5\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii is (\displaystyle a).

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 14

Now solve for \displaystyle a

\displaystyle a = 7.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = - \frac{1}{2} \\\\y = -1.0

So the center of the foci is at \displaystyle \left ( - \frac{1}{2}, \quad -1\right )

Now we need to figure out what the distance from the center to the foci \displaystyle c.

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = - \frac{11}{2}

Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 7.0 and \displaystyle c with \displaystyle - \frac{11}{2}

\displaystyle b^{2} = 18.75

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{49} \left(x + \frac{1}{2}\right)^{2} + \frac{4}{75} \left(y + 1\right)^{2} = 1

 

 

Example Question #9 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (-8, -5 ) and \displaystyle (3, -5) with a major axis distance of \displaystyle 18.

 

 

Possible Answers:

\displaystyle \frac{x^{2}}{18} + \frac{y^{2}}{18} = 1

\displaystyle 18 x^{2} + 18 y^{2} = 1

\displaystyle \frac{1}{18} \left(x + 8\right)^{2} + \frac{1}{18} \left(y + 5\right)^{2} = 1

\displaystyle \frac{1}{81} \left(x + \frac{5}{2}\right)^{2} + \frac{4}{203} \left(y + 5\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

Correct answer:

\displaystyle \frac{1}{81} \left(x + \frac{5}{2}\right)^{2} + \frac{4}{203} \left(y + 5\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x + 8\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii is (\displaystyle a).

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 18

Now solve for \displaystyle a

\displaystyle a = 9.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = - \frac{5}{2} \\\\y = -5.0

So the center of the foci is at \displaystyle \left ( - \frac{5}{2}, \quad -5\right )

Now we need to figure out what the distance from the center to the foci is (\displaystyle c).

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = \frac{11}{2}
Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 9.0 and \displaystyle c with \displaystyle \frac{11}{2}

\displaystyle b^{2} = 50.75

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{81} \left(x + \frac{5}{2}\right)^{2} + \frac{4}{203} \left(y + 5\right)^{2} = 1

 

 

Example Question #10 : Derive Ellipse And Hyperbola Equations: Ccss.Math.Content.Hsg Gpe.A.3

Find the equation of an ellipse that has foci at \displaystyle (7, -1) and \displaystyle (0, -1) with a major axis distance of \displaystyle 16.

Possible Answers:

\displaystyle \frac{x^{2}}{16} + \frac{y^{2}}{16} = 1

\displaystyle \frac{1}{64} \left(x - \frac{7}{2}\right)^{2} + \frac{4}{207} \left(y + 1\right)^{2} = 1

\displaystyle x^{2} + y^{2} = 1

\displaystyle 16 x^{2} + 16 y^{2} = 1

\displaystyle \frac{1}{16} \left(x - 7\right)^{2} + \frac{1}{16} \left(y + 1\right)^{2} = 1

Correct answer:

\displaystyle \frac{1}{64} \left(x - \frac{7}{2}\right)^{2} + \frac{4}{207} \left(y + 1\right)^{2} = 1

Explanation:

The general equation is

\displaystyle \frac{1}{b^{2}} \left(- h + y\right)^{2} + \frac{1}{a^{2}} \left(x - 7\right)^{2} = 1

\displaystyle \left ( k, \quad h\right ) is the coordinates of the center of the foci.

\displaystyle a is the distance to the foci on the x-axis from the center, and \displaystyle b is the distance to the foci from the y-axis.

The first step is to figure out what the focal radii is ().

Since we know the distance of the major axis, all we need to do is set up a simple equation.

\displaystyle 2 a = 16

Now solve for \displaystyle a

\displaystyle a = 8.0

The next step is to find the center between the foci.

To find the center, we simply find the average between the coordinates.

\displaystyle \\x = \frac{7}{2} \\\\y = -1.0

So the center of the foci is at \displaystyle \left ( \frac{7}{2}, \quad -1\right )

Now we need to figure out what the distance from the center to the foci is ().

We do this by taking the x-coordinate from one of the foci and subtracting it from the center x-coordinate

\displaystyle c = - \frac{7}{2}
Now the last part is to find \displaystyle b.

We can find it by using the following equation.

\displaystyle b^{2} = a^{2} - c^{2}

We simply substitute \displaystyle a with 8.0 and \displaystyle c with \displaystyle - \frac{7}{2}

\displaystyle b^{2} = 51.75

Now we can substitute these values into the general equation to get.

\displaystyle \frac{1}{64} \left(x - \frac{7}{2}\right)^{2} + \frac{4}{207} \left(y + 1\right)^{2} = 1 

 

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