y2/B2 = 1(a & gt； B>0), r 1 and r2 are the distances between point m and points f 1(-c, 0) and f2(c, 0), then (left focal length) r 1=a+ex0, (right focal length) R2 = a.

-ex0, where e is eccentricity.

Deduction: r 1/∣mn 1∣=

r2/∣mn2∣=e

Available: r 1=

e∣mn 1∣=

e(a^2/

c+x0)=

a+ex0，r2=

e∣mn2∣=

e(a^2/

c-x0)=

a-ex0 .

Similarly: ∣mf 1∣=

a+ey0,∣mf2∣=

A-ey0 .2. The focal radius formula of hyperbola The focal radius formula when point P is on the right branch of hyperbola (where f 1 is the left focus and f2 is the right focus) is derived from the second definition, where a is the real semi-axis length, e is the eccentricity and x is the eccentricity. Is the abscissa of point p. |pf2|=ex。 -

a

And only remember that the right branch, the left branch and the right branch are just a negative sign.

If the focus is on the y axis, just remember the above branch in the same way.

Radius of hyperbola passing through right focal point r = | a-ex |

The radius of hyperbola passing through the left focus is r = | a+ex | 3. Parabola Parabola's focal radius formula r=x+p/2.

Diameter: the chord of a conic curve (except a circle) passing through the focal point and perpendicular to the axis.

The path of hyperbola and ellipse is 2b 2/a, and the focal length is a 2/c-c-c.

The path of the parabola is 2p.

Parabola y 2 = 2px

(p>0), c(xo, yo) is a point on a parabola, and the focal radius |cf|=xo+p/2.