Conics
Definition
A conic is defined as the locus of a point, which moves such that its distance
from a fixed line to its distance from a fixed point is always constant. The fixed point is
called the focus of the conic. The fixed line is called the directrix of the conic. The
constant ratio is the eccentricity of the conic.
L
M P
F
L is the fixed line โ Directrix of the conic.
F is the fixed point โ Focus of the conic.
=
PM
FP
constant ratio is called the eccentricity = โeโ
Classification of conics with respect to eccentricity
1. If e < 1, then the conic is an Ellipse
M1 M2
L2 B L1
A1 A
LI 2 LI 1
BI
M21
M11
1) The standard equation of an ellipse is
1
2
2
2
2
=+ b
y
a
x
O
F
2
F
1
S
SI
