All Precalculus Resources
Example Questions
Example Question #11 : Understand Features Of Hyperbolas And Ellipses
Find the center of the ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
For the equation given in the question, and
.
The center of the ellipse is at .
Example Question #11 : Hyperbolas And Ellipses
Find the center of the ellipse with the following equation:
Start by putting the equation back into the standard equation of the ellipse:
, where
is the center for the ellipse.
Group the terms and
terms together.
Factor out a from the
terms, and a
from the
terms.
Now, complete the square. Remember to add the same amounts on both sides of the equation.
Now, divide both sides by .
Finally, factor the equations to get the standard form of the equation for an ellipse.
Since and
, the center for this ellipse is
.
Example Question #12 : Hyperbolas And Ellipses
Find the center of the ellipse with the following equation:
Start by putting the equation back into the standard equation of the ellipse:
, where
is the center for the ellipse.
Group the terms and
terms together.
Factor out a from the
terms and a
from the
terms.
Now, complete the squares. Make sure you add the same amount on both sides!
Subtract from both sides.
Now, divide both sides by .
Finally, factor the terms to get the standard form of the equation of an ellipse.
Since and
, the center of the ellipse is
.
Example Question #11 : Understand Features Of Hyperbolas And Ellipses
Find the center of the ellipse with the following equation:
Start by putting the equation back into the standard equation of the ellipse:
, where
is the center for the ellipse.
Group the terms and
terms together.
Factor out a from the
terms and a
from the
terms.
Now, complete the squares. Remember to add the same amount on both sides!
Subtract from both sides.
Divide both sides by .
Finally, factor the terms to get the standard form of the equation of an ellipse.
Since and
,
is the center of this ellipse.
Example Question #101 : Conic Sections
Find the foci of an ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
When , the major axis will lie on the
-axis and be horizontal. When
, the major axis will lie on the
-axis and be vertical.
Recall also that the distance from the center to a focus, , is given by the equation
when
, and the equation is
when
.
When the major axis follows the -axis, the points for the foci are
and
.
When the major axis follows the -axis, the points for the foci are
and
.
For the given equation, the center is at . Since
, the major-axis is vertical.
Plug in the values to solve for .
Now, add to the y-coordinate of the center to get one focus. Subtract
from the y-coordinate of the center to get the other focus point.
The foci for the ellipse is then and
.
Example Question #106 : Conic Sections
Find the foci of the ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
When , the major axis will lie on the
-axis and be horizontal. When
, the major axis will lie on the
-axis and be vertical.
Recall also that the distance from the center to a focus, , is given by the equation
when
, and the equation is
when
.
When the major axis follows the -axis, the points for the foci are
and
.
When the major axis follows the -axis, the points for the foci are
and
.
Start by putting the equation into the standard form of the equation of an ellipse.
Group the and
terms together.
Now, factor out a from the
terms and a
from the
terms.
Complete the squares. Remember to add the same amount to both sides of the equation!
Subtract from both sides of the equation.
Divide both sides by .
Factor both terms to get the standard form of the equation of an ellipse.
Now, the center for this ellipse is and its major axis is horizontal.
Next, solve for .
The foci for this ellipse are then at and
.
Example Question #12 : Hyperbolas And Ellipses
Find the foci for the ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
When , the major axis will lie on the
-axis and be horizontal. When
, the major axis will lie on the
-axis and be vertical.
Recall also that the distance from the center to a focus, , is given by the equation
when
, and the equation is
when
.
When the major axis follows the -axis, the points for the foci are
and
.
When the major axis follows the -axis, the points for the foci are
and
.
For the given equation, the center is at . Since
, the major-axis is horizontal.
Plug in the values to solve for .
The foci are then at the points and
.
Example Question #1691 : Pre Calculus
Find the foci of the ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
When , the major axis will lie on the
-axis and be horizontal. When
, the major axis will lie on the
-axis and be vertical.
Recall also that the distance from the center to a focus, , is given by the equation
when
, and the equation is
when
.
When the major axis follows the -axis, the points for the foci are
and
.
When the major axis follows the -axis, the points for the foci are
and
.
Start by putting the equation into the standard form of the equation of an ellipse.
Group the and
terms together.
Factor out a from the
terms and a
from the
terms.
Now, complete the squares. Remember to add the same amount to both sides of the equation!
Subtract from both sides.
Divide both sides by .
Now, factor both terms to get the standard form of the equation of an ellipse.
The center of the ellipse is . Since
, the major axis of this ellipse is horizontal.
Now, find the value of .
The foci of this ellipse are then and
.
Example Question #19 : Understand Features Of Hyperbolas And Ellipses
Find the foci of an ellipse with the following equation:
Recall that the standard form of the equation of an ellipse is
, where
is the center for the ellipse.
When , the major axis will lie on the
-axis and be horizontal. When
, the major axis will lie on the
-axis and be vertical.
Recall also that the distance from the center to a focus, , is given by the equation
when
, and the equation is
when
.
When the major axis follows the -axis, the points for the foci are
and
.
When the major axis follows the -axis, the points for the foci are
and
.
Start by putting the equation into the standard form of the equation of an ellipse.
Group the and
terms together.
Factor out from the
terms and a
from the
terms.
Now, complete the squares. Remember to add the same amount to both sides of the equation!
Subtract both sides by .
Divide both sides by .
Factor both terms to get the standard form of the equation of an ellipse.
The center of this ellipse is at . Since
, the major axis of this ellipse is vertical.
Now, solve for .
The foci for this ellipse are then and
.
Example Question #11 : Hyperbolas And Ellipses
Find the center and foci of the ellipse
.
Center: ; Foci:
Center: ; Foci:
Center: ; Foci:
Center: ; Foci:
Center: ; Foci:
Center: ; Foci:
The center of this ellipse is . The number under
is bigger than the number under
, so the major axis goes up and down. The foci will also be on the major axis, so their x-coordinates will be 0, like the center.
To figure out the distance from the center to the foci, we can use the formula where a is half the major axis, b is half the minor axis, and c is the distance from the center to the foci.
In this case, and
:
subtract 36 from both sides
multiply both sides by -1
take the square root
This means that since the center is , the foci are located at
and
.
All Precalculus Resources
![Learning Tools by Varsity Tutors](https://vt-vtwa-app-assets.varsitytutors.com/assets/problems/og_image_practice_problems-9cd7cd1b01009043c4576617bc620d0d5f9d58294f59b6d6556fd8365f7440cf.jpg)