Circle
(x − h)2 + (y − k)2 = r 2
Parabola
y − k = a(x − h)2
x − h = a(y − k)2
1
a=
4c
Ellipse
x 2 y2
+ =1
a2 b2
x 2 y2
+ =1
b2 a2
b2 = a2 − c2
c = a2 − b2
Sum of focal radii = 2a
Hyperbola
x 2 y2
− =1
a2 b2
b
b
y= x y=− x
a
a
2
2
y x
− =1
a2 b2
a
a
y= x y=− x
b
b
2
2
2
b =c −a
c = a2 + b2
Difference of focal radii
= 2a
Circle
(x − h)2 + (y − k)2 = r 2
Parabola
y − k = a(x − h)2
x − h = a(y − k)2
1
a=
4c
Ellipse
x 2 y2
+ =1
a2 b2
x 2 y2
+ =1
b2 a2
b2 = a2 − c2
c = a2 − b2
Sum of focal radii = 2a
Hyperbola
x 2 y2
− =1
a2 b2
b
b
y= x y=− x
a
a
2
2
y x
− =1
a2 b2
a
a
y= x y=− x
b
b
2
2
2
b =c −a
c = a2 + b2
Difference of focal radii
= 2a
Circle
(x − h)2 + (y − k)2 = r 2
Parabola
y − k = a(x − h)2
x − h = a(y − k)2
1
a=
4c
Ellipse
x 2 y2
+ =1
a2 b2
x 2 y2
+ =1
b2 a2
b2 = a2 − c2
c = a2 − b2
Sum of focal radii = 2a
Hyperbola
x 2 y2
− =1
a2 b2
b
b
y= x y=− x
a
a
2
2
y x
− =1
a2 b2
a
a
y= x y=− x
b
b
2
2
2
b =c −a
c = a2 + b2
Difference of focal radii
= 2a