Solution - Properties of ellipses
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Properties of ellipsesStep-by-step explanation
1. Find the standard form
To find the standard form of an ellipse, make the right side of the equation equal to :
Divide both sides by 6
Simplify the expression
Because the denominator of x is bigger than the denominator of y , it represents the major axis , making this a horizontal ellipse equation:
2. Find the center
represents the x-offset from the origin.
represents the y-offset from the origin.
To find the values of and , use the horizontal ellipse standard form:
Center:
3. Find the radius of the major axis
represents the longer radius of the ellipse, which is equal to half of the major axis. This is called the semi-major axis.
To find the value of , use the horizontal ellipse standard form:
Take the square root of both sides of the equation:
Because represents a distance, it only has a positive value.
4. Find the vertices
In a horizontal ellipse, the major axis runs parallel to the x-axis and passes through the ellipse's vertices. Find the vertices by adding and subtracting from the x-coordinate of the center.
To find vertex_1, add to the x-coordinate of the center:
Vertex_1:
Center:
Vertex_1:
Vertex_1:
To find vertex_2, subtract from the x-coordinate () of the center:
Vertex_2:
Center:
Vertex_2:
Vertex_2:
5. Find the radius of the minor axis
represents the shorter radius of the ellipse, which is equal to half of the minor axis. This is called the semi-minor axis.
To find the value of , use the horizontal ellipse standard form:
Take the square root of both sides of the equation:
Because b represents a distance, it only has a positive value.
6. Find the co-vertices
In a horizontal ellipse, the minor axis runs parallel to the y-axis and passes through the ellipse's co-vertices.
Find the co-vertices by adding and subtracting from the y-coordinate of the center.
To find co-vertex_1, add to the y coordinate of the center:
Co-vertex_1:
Center:
Co-vertex_1:
Co-vertex_1:
To find co-vertex_2, subtract from the y-coordinate of the center:
Co-vertex_2:
Center:
Co-vertex_2:
Co-vertex_2:
7. Find the focal length
Focal length is the distance from the ellipse's center to each focal point and is usually represented by .
To find , use the formula:
Plug and into the formula and simplify:
Because represents a distance, it only has a positive value.
8. Find the foci
In a horizontal ellipse, the major axis runs parallel to the x-axis and through the foci.
Find the foci by adding and subtracting from the x-coordinate of the center.
To find focus_1, add to the x-coordinate of the center:
Focus_1:
Center:
Focus_1:
Focus_1:
To find focus_2, subtract from the x-coordinate of the center:
Focus_2:
Center:
Focus_2:
Focus_2:
9. Find the area
Use the formula for the area of an ellipse to find the ellipse's area:
Plug and into the formula and simplify:
The area equals
10. Find the x and y-intercepts
To find the x-intercept(s), plug in for in the ellipse's standard equation and solve the resulting quadratic equation for .
Click here for a step-by-step explanation of the quadratic equation.
To find the y-intercept(s), plug in for in the ellipse's standard equation and solve the resulting quadratic equation for .
Click here for a step-by-step explanation of the quadratic equation.
11. Find the eccentricity
To find the eccentricity use the formula:
Plug , and into the formula:
The eccentricity equals
12. Graph
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Please leave us feedback.Why learn this
If you cut a carrot in half across its grain (like this: =|> ) the resulting cross-section would be circular and, therefore, somewhat easy to measure. But what if you cut the same carrot across the grain at an angle (like this: =/> )? The resulting shape would be more of an ellipse and measuring it would prove to be a bit more difficult than measuring a plain old circle. But why would you need to measure the cross section of a carrot to begin with?
Well... you probably would not, but such occurrences of ellipses in nature are actually quite common, and understanding them from a mathematical perspective can be useful in many different contexts. Fields such as art, design, architecture, engineering, and astronomy all rely at times on ellipses - from painting portraits, to building homes, to measuring the orbit of moons, planets, and comets.