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What is the focal length of ellipse? What is the formula?
The focal length of an ellipse refers to the distance between the two focal points of an ellipse. Calculation formula: focal length =2c.

An ellipse is the trajectory of a moving point P. The sum of the distances from the moving point P to the fixed points F 1 and F2 in a plane is equal to a constant (greater than |F 1F2|), and F1and F2 are called the two focuses of the ellipse. The mathematical expression is | pf1|+pf2 | = 2a (2a > | f1F2 |).

The focal length of an ellipse is the first definition of an ellipse:

Among them, two fixed points F 1 and F2 are called the focal points of an ellipse, the distance between the two focal points │F 1F2│=2c, and the focal length =2c.

Extended data:

In the standard equation of ellipse x 2/a 2+y 2/b 2 =1,if a >:b>;; 0 the focus is on the x axis; If the b>a> focus is on the y axis. At this time, a stands for the major axis and b stands for the minor axis.

C represents half the distance between two focal points, and there is a 2 = c 2+b 2.

Eccentricity e=c/a

(0<e< 1), the larger e, the flatter the ellipse. Eccentricity of ellipse is 0.

Parametric equation of ellipse x=acosθ.

y=bsinθ.

When solving the maximum distance from a point on an ellipse to a fixed point or a fixed line, the problem can be transformed into a trigonometric function problem by solving x=a×cosβ with parametric coordinates.

y=b×sinβ

A is half the length of the spindle.

B is half the length of the minor axis.

References:

Baidu encyclopedia-ellipse