 ### 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 With Axes

Illustration of an ellipse with major and minor axes. ### 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.