ellipse
(noun)
The conic section formed by the plane being at an angle to the base of the cone.
(noun)
One of the conic sections.
Examples of ellipse in the following topics:
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Ellipses as Conic Sections
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Parts of an Ellipse
- Ellipses are one of the types of conic sections.
- The standard form for the equation of the ellipse is:
- if the ellipse is oriented vertically.
- For a vertical ellipse, the association is reversed.
- An eccentricity of $1$ is a parabola, not an ellipse.
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Ellipses
- And the resulting shape will be an ellipse.
- How often do ellipses come up in real life?
- The sun is at one focus of the ellipse (not at the center).
- If a>b, the ellipse is horizontal.
- If a, the the ellipse is vertical.
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Introduction to Ellipses
- An ellipse is one of the shapes called conic sections, which is formed by the intersection of a plane with a right circular cone.
- The general equation of an ellipse centered at $\left(h,k\right)$ is:
- which is exactly the equation of a horizontal ellipse centered at the origin.
- An ellipse is a conic section, formed by the intersection of a plane with a right circular cone.
- Connect the equation for an ellipse to the equation for a circle with stretching factors
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Kepler's First Law
- The orbit of every planet is an ellipse with the Sun at one of the two foci.
- An ellipse is a closed plane curve that resembles a stretched out circle.
- A circle is a special case of an ellipse where both focal points coincide.
- where $(r, \theta)$ are the polar coordinates (from the focus) for the ellipse, $p$ is the semi-latus rectum, and $\epsilon$ is the eccentricity of the ellipse.
- Heliocentric coordinate system $(r, \theta)$ for ellipse.
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Planetary Motion According to Kepler and Newton
- Kepler explained that the planets move in an ellipse around the Sun, which is at one of the two foci of the ellipse.
- The eccentricity of an ellipse tells you how stretched out the ellipse is.
- The eccentricity is what makes an ellipse different from a circle.
- Therefore, the period ($P$) of the ellipse satisfies:
- The important components of an ellipse are as follows: semi-major axis $a$, semi-minor axis $b$, semi-latus rectum $p$, the center of the ellipse, and its two foci marked by large dots.
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What Are Conic Sections?
- The three types of conic sections are the hyperbola, the parabola, and the ellipse.
- In the case of an ellipse, there are two foci, and two directrices.
- In the next figure, a typical ellipse is graphed as it appears on the coordinate plane.
- They could follow ellipses, parabolas, or hyperbolas, depending on their properties.
- The sum of the distances from any point on the ellipse to the foci is constant.
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Conic Sections in Polar Coordinates
- Traditionally, the three types of conic section are the hyperbola, the parabola, and the ellipse.
- The circle is a special case of the ellipse, and is of such sufficient interest in its own right that it is sometimes called the fourth type of conic section.
- The type of a conic corresponds to its eccentricity, those with eccentricity less than 1 being ellipses, those with eccentricity equal to 1 being parabolas, and those with eccentricity greater than 1 being hyperbolas.
- As in the figure, for $e = 0$, we have a circle, for $0 < e < 1$ we obtain an ellipse, for $e = 1$ a parabola, and for $e > 1$ a hyperbola.
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Types of Conic Sections
- The definition of an ellipse includes being parallel to the base of the cone as well, so all circles are a special case of the ellipse.
- Ellipses have these features:
- A major axis, which is the longest width across the ellipse
- A minor axis, which is the shortest width across the ellipse
- Ellipses can have a range of eccentricity values: $0 \leq e < 1$.
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Conic Sections
- Traditionally, the three types of conic section are the hyperbola, the parabola, and the ellipse.
- The circle is a special case of the ellipse, and is of such interest in its own right that it is sometimes called the fourth type of conic section.
- The type of a conic corresponds to its eccentricity—those with eccentricity less than 1 being ellipses, those with eccentricity equal to 1 being parabolas, and those with eccentricity greater than 1 being hyperbolas.
- If they are bound together, they will both trace out ellipses; if they are moving apart, they will both follow parabolas or hyperbolas.
- Ellipse; 3.