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Example Questions
Example Question #1 : Understand Features Of Hyperbolas And Ellipses
Find the equation of an ellipse centered at the origin if the major axis is parallel to the x-axis and has a length of units and the minor axis has a length of units.
The formula for an ellipse centered at the point with a horizontal major axis (ie: parallel to the x-axis) has the formula
where and are the lengths of the major and minor axes respectively.
Since the origin is at and and in this problem, the equation is
or
Example Question #1 : Understand Features Of Hyperbolas And Ellipses
The equation of an ellipse, , is . Which of the following is the correct center and foci of this ellipse?
Center=, Foci= and
Center=, Foci= and
Center=, Foci= and
Center=, Foci= and
Center=, Foci= and
Center=, Foci= and
Because our equation is already in the format
,
we do not have to manipulate the equation. The center of any ellipse in this form will always be . So in this case, our center will be . To find the foci of the ellipse, we must use the equation , where is the greater of the two denominators in our equation ( and ), is the lesser and is the distance from the center to the foci.
We know that and .
By using , we see that , so .
We now know that the two foci are going to be units in either direction of the center along the greater axis.
Because the greater denominator is under our term containing , our ellipse will have its greater axis going vertically, rather than horizontally. Therefore, our foci will be units above and below our center, at and .
Example Question #4 : 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 #4 : 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:
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 #15 : 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 .
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 .
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