Latus rectum is also called path. A special focal string. Refers to the chord passing through the focus of the conic curve and parallel to the guide line, which is perpendicular to the axis passing through the focus.
parabola Is a kind of A conic curve or a parabola is a curve through which an object is thrown and falls on the ground in the distance. 。 In a plane, each point of the parabola P i The distance between it and a fixed point F is equal to the distance between it and a fixed line L that does not pass through this point F. The fixed point F is called the "focus" of the parabola, and the fixed straight line L is called the "directrix" of the parabola. [1]
Alignment and focus: see above.
Vertex: the intersection of a parabola and its axis is called parabola vertex 。
Chords: parabolic string It connects any two points on the parabola line segment 。 Sine chord: parabolic Sine chord Is the focal chord perpendicular to the axis.
Focal chord: parabolic Focal chord Is the chord passing through the focus of the parabola.
Diameter: parabolic diameter Is the locus of the midpoint of a group of parallel chords of a parabola. This diameter is also called the conjugate diameter 。 Main diameter: parabolic Main diameter Is the axis of the parabola. [1]
The light emitted by the point light source at the focus is parallel to the axis of symmetry of the parabola after being reflected by the parabola. Typical applications are flashlights.
- one
The intersection point of the tangents passing through the two ends of the focal chord of the parabola is on the directrix of the parabola.
- two
The tangents at both ends of the focal chord passing through the parabola are perpendicular to each other.
- three
The circle whose diameter is the focal chord of the parabola is tangent to the directrix of the parabola.
- four
The intersection point of the tangents passing through the two ends of the parabolic focal chord is perpendicular to the line connecting the focus of the parabola and the focus chord.
- five
The intersection of the tangents at both ends of the focus chord and the line connecting the midpoint of the focus chord are bisected by a parabola.
- six
One end of the focus chord is used as the vertical line of the guide line, and the vertical foot, the vertex and the other end of the focus chord are collinear.
- seven
The two ends of the focal chord are used as the perpendicular lines of the collimation line, and the connecting lines between the two perpendicular feet and the focus of the parabola are perpendicular to each other. [2]
