### Approximate Ellipse using Lines

"When the minor axis is at least two-thirds the major, the following method ma be used: Make CF and…

### Approximate Ellipse with Five Centered Arc

"This (five centered arc) method is based on the principle that the radius of curvature at the end of…

### Approximate Ellipse with Four Centers

"Join A and D. Lay off DF equal to AC-DC. Bisect AF by a perpendicular crossing AC at G and intersecting…

### Circular Involution

Every elliptical involution has the property that there are two definite points in the plane from which…

### Cone

Sections of a cone. a, parabola; b, ellipse; c, hyperbola.

### Conic Involution

The lines which join corresponding points in an involution on a conic all pass through a fixed point;…

### Conic Sections

Conic sections, cones divided by a plane.

### Cone depicting Conic Sections

Diagram of a cone with spheres and cut by a plane to depict the conic sections.

### Cone depicting Conic Sections

Diagram of a cone with inscribed spheres and cut by various planes to depict the conic sections: circle,…

### Construction of a Conic

Diagram showing how to construct a conic when given the focus and the auxiliary circle. If the focus…

### Focus In Auxiliary Circle of Conic

Diagram showing how to construct a conic when given the focus and the auxiliary circle. The focus is…

### Focus In Auxiliary Circle of Conic

Diagram showing how to construct a conic when given the focus and the auxiliary circle. As the focus…

### Construction of Ellipse using Ellipsograph

An ellipsograph uses the trammel method to create ellipses.

### Construction of Ellipse using Parallelogram

Create diameters with major, minor axes, or a pair of conjugate diameters. Construct a parallelogram,…

### Construction of Ellipse using Pin and String

An ellipse can be constructed by pinning three pins and tying an inelastic in tightly around the pins.

### Construction of Ellipse using Trammel Method

Trammel method is a construction of an ellipse using a strip of paper, thin cardboard or sheet celluloid.

### Curve Inked with Circle Arcs

"Any noncircular curve may be approximated by tangent circle arcs, selecting a center by trial, drawing…

### Plane Intersecting A Cylinder

Illustration of a cylinder cut by a plane making an angle of 57° with the base.

### Projection of Cylinder

Illustration of the method of finding the projection, in the form of an ellipse, of the top of a cylinder…

### Determining Points on Ellipse Using Circles

Using C as a center, draw two circles with different diameters. The intersection of the diameter lines…

### Eccentric Angle

"In geometry, an angle connected with an ellipse and defined as ... angle BCL, reckoned from one determinate…

### Ellipse

One of the three species of conic sections is the ellipse.

### Ellipse

Illustration of an ellipse with major and minor axes, foci, and points on the ellipse. "An ellipse is…

### Ellipse

Illustration of an ellipse.

### Ellipse

Illustration of an ellipse.

### Ellipse

Illustration of an ellipse.

### Ellipse With Axes

Illustration of an ellipse with major and minor axes.

### Ellipse

Illustration of an ellipse.

### Ellipse

Illustration showing an ellipse formed by the intersection of the surface of a cone with a plane neither…

### Corresponding Points in an Ellipse and Circle

Illustration of half of an ellipse. "The ordinates of two corresponding points in an ellipse and its…

### Construction of Ellipse by Describing Circles

Illustration used to draw a an ellipse using string and pins by describing a circles with diameters…

### Construction Of An Ellipse Tangent To Two Parallel Lines

An illustration showing how to construct an ellipse parallel to two parallel lines A and B. "Draw a…

### Construction of Ellipse Using String

Illustration used to draw a an ellipse using string and pins.

### Area of Ellipse

Illustration of a ellipse with squares drawn to demonstrate area.

### Area of an Ellipse

Illustration of half of an ellipse used to show that the area of an ellipse is equal to pi times a times…

### Conic Section Showing an Ellipse

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular…

### Conic Section Showing an Ellipse

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular…

### Conic Section Showing Ellipse

Illustration showing the definition of an ellipse as a conic section. The plane cuts the cone obliquely.

### Conic Section Showing An Ellipse

Illustration showing the definition of an ellipse as a conic section. The section of a right circular…

### Conic Section Showing An Ellipse

An illustration showing the intersection of a plane and a cone. The cone is intersected by a plane neither…

### Conjugate Diameters of an Ellipse

Illustration showing that if one diameter is conjugate to a second, the second is conjugate to the first.

### Construction of an Ellipse

Illustration of half of an ellipse and its auxiliary circle used to construct an ellipse by points,…

### Construction Of An Ellipse

An illustration showing how to construct an ellipse. "With a as a center, draw two concentric circles…

### Construction Of An Ellipse

An illustration showing how to construct an ellipse using a string. "Having given the two axes, set…

### Construction Of An Ellipse

An illustration showing how to construct an ellipse using circle arcs. "Divide the long axis into three…

### Construction Of An Ellipse

An illustration showing how to construct an ellipse using circle arcs. "Given the two axes, set off…

### Construction Of An Ellipse

An illustration showing how to construct an ellipse. Given the two axes, set off half the long axis…

### Construction of Ellipse

Illustration used to draw a an ellipse with major axis AB and minor axis CD.

### Construction of an Ellipse

Diagram showing how to construct an ellipse when given the two foci and the length of the major axis…

### Definition of Ellipse

Diagram of an ellipse that can used to illustrate the definition. "The constant ration between the distances…

### Demonstration of Ellipse Definition

Illustration showing the definition of an ellipse. "An ellipse is a curve which is the locus of a point…

### Focal Radii of an Ellipse

Illustration of half of an ellipse. "If d denotes the abscissa of a point of an ellipse, r and r' its…

### Foci Distances on an Ellipse

Diagram that illustrates "The algebraic sum of the distances of any point from the foci of a conic is…

### Graph of Ellipse with Foci and Center Labeled

A graph of tan ellipse with Foci and Center.

### Ellipse Inscribed In A Circle

Illustration of an ellipse, whose major axis is vertical, inscribed in a circle whose diameter is equal…

### Ellipse With Parts Labeled

Illustration of an ellipse with foci F' and F, major axis A' to A, minor axis B' to B, and center O.

### Line Bisecting Angle Between Focal Radii on Ellipse

Illustration of half of an ellipse. "If through a point P of an ellipse a line is drawn bisecting the…

### Ordinate and Major Axis of Ellipse

Illustration of half of an ellipse. The square of the ordinate of a point in an ellipse is to the product…

### Parallel Tangents to an Ellipse

Illustration showing that tangents drawn at the ends of any diameter are parallel to each other.

### Ellipse With Parts Labeled

Illustration of ellipse with parts labeled.