In mathematics, an ellipse is a curve around two focal points on a plane, so for each point on the curve, the sum of the distances to the two focal points is constant. Therefore, it is a generalization of a circle, and it is a special type of ellipse with two focuses at the same position. The shape of an ellipse (how to "stretch") is expressed by its eccentricity, which can be any number from 0 (the limit case of a circle) to close to but less than 1.
An ellipse is a closed cone section: a plane curve intersects a plane through a cone. Ellipse has many similarities with the other two forms of conical section: parabola and hyperbola, which are both open and unbounded. The cross section of a cylinder is elliptical unless it is perpendicular to the axis of the cylinder.
An ellipse can also be defined as a set of points, so that the ratio of the distance between each point on the curve and a given point (called focus) to the distance between the same point on the curve (called directrix) is a constant. This ratio is called eccentricity of ellipse.
Ellipse hand-drawing method:
The focal length of an ellipse │FF'│(Z) is defined. It is known that the major axis X(ab) and minor axis Y(cd) formed by an ellipse draw an arc with one end of the major axis A as the center and the minor axis Y as the radius, and the line segment tangent to the arc from the other point B of the major axis is the focal length of the ellipse. The verification formula is 2 √ {(z/2) 2+(y/2). |FF'|) is called ellipse), which can evolve into z = √ x2-y2 (x >; y & gt0)。
The two endpoints f and f' of z are fixed points. Take a tough line, and the smaller the expansion coefficient, the better. Take any group of line segments AF' or FB as the length, take this length as the perimeter of a fixed triangle, take F and F' as the fixed points, and draw an arc with the third point on the triangle as the moving point to form an ellipse.