The focal radius formulas of ellipse, hyperbola and parabola, please be more detailed. What does each letter mean? Thank you for returning to the three-day college entrance examination.

Elliptic focal radius

Let M(x0, y0) be an ellipse x? /a？ +y？ /b？ = 1(a >b & gt0),

The focal radius r 1 and r2 are the distances between point m and point F 1(-c, 0), F2(c, 0), and e is eccentricity.

Then r 1=a+ex0, r2=a-ex0,

Let M(x0, y0) be an ellipse x? /b？ +y？ /a？ = 1(a >b & gt0),

The focal radius r 1 and r2 are the distances between point m and point F 1(0, -c), F2(0, c), and e is eccentricity.

Then r 1=a+ey0, r2=a-ey0,

Hyperbolic focal radius

Let M(x0, y0) be a hyperbola x? /a？ -Really? /b？ = 1,

The focal radius r 1 and r2 are the distances between point m and point F 1(-c, 0), F2(c, 0), and e is eccentricity.

Right focus radius r=|ex0-a| Left focus radius r=|ex0+a|

Let M(x0, y0) be a hyperbola y? /a？ -x？ /b？ = 1,

The focal radius r 1 and r2 are the distances between point m and point F 1(0, -c), F2(0, c), and e is eccentricity.

Right focus radius r=|ey0-a| Left focus radius r=|ey0+a|

Parabolic focal radius

Let M(x0, y0) parabola y? =2px, and the focal radius is r=x0+p/2.

Let M(x0, y0) parabola x? =2py, and the focal radius is r=y0+p/2.