Search results
Results From The WOW.Com Content Network
For a parabola, the semi-latus rectum, , is the distance of the focus from the directrix. Using the parameter p {\displaystyle p} , the equation of the parabola can be rewritten as x 2 = 2 p y . {\displaystyle x^{2}=2py.}
where e is the eccentricity and l is the semi-latus rectum. As above, for e = 0, the graph is a circle, for 0 < e < 1 the graph is an ellipse, for e = 1 a parabola, and for e > 1 a hyperbola. The polar form of the equation of a conic is often used in dynamics; for instance, determining the orbits of objects revolving about the Sun. [20]
The length of the chord through one of the foci, perpendicular to the major axis of the hyperbola, is called the latus rectum. One half of it is the semi-latus rectum. A calculation shows =. The semi-latus rectum may also be viewed as the radius of curvature at the vertices.
The universal parabolic constant is the red length divided by the green length. The universal parabolic constant is a mathematical constant.. It is defined as the ratio, for any parabola, of the arc length of the parabolic segment formed by the latus rectum to the focal parameter.
The area formula is intuitive: start with a circle of radius (so its area is ) and stretch it by a factor / to make an ellipse. This scales the area by the same factor: π b 2 ( a / b ) = π a b . {\displaystyle \pi b^{2}(a/b)=\pi ab.} [ 18 ] However, using the same approach for the circumference would be fallacious – compare the integrals
Every parabola with focus at the origin and x-axis as its axis of symmetry is the locus of points satisfying the equation y 2 = 2 x p + p 2 , {\displaystyle y^{2}=2xp+p^{2},} for some value of the parameter p , {\displaystyle p,} where | p | {\displaystyle |p|} is the semi-latus rectum.
A parabola can be obtained as the limit of a sequence of ellipses where one focus is kept fixed as the other is allowed to move arbitrarily far away in one direction, keeping fixed. Thus a and b tend to infinity, a faster than b. The length of the semi-minor axis could also be found using the following formula: [2]
Menaechmus knew that in a parabola y 2 = Lx, where L is a constant called the latus rectum, although he was not aware of the fact that any equation in two unknowns determines a curve. [4] He apparently derived these properties of conic sections and others as well.