2. α β
THE INTERSECTION OF A PLANE WITH A CONE,
THE SECTION SO OBTAINED IS CALLED A
CONIC SECTION
V
m
Lower
nappe
Upper
nappe
Axis
Generator
l
This is a conic section.
14. A PARABOLA IS THE
SET OF ALL POINTS
IN A PLANE THAT
ARE EQUIDISTANT
FROM A FIXED POINT
A
B
V
PARABOLA
(VERTEX)
F
( focus)
1 2 3 4O
P
1
P2
15. α
β
F(a,0)O
x=-a
y² = 4ax
X' X
Y'
Y
F(-a,0) O
x=+a
y² = -4ax
X' X
Y'
Y
F(0,-a)
O
y = a
x² = 4ay
X' X
Y'
Y
F(0,a)
O
y = -a
x² = -4ay
X' X
Y'
Y
When α = β, the section is an parabola
Horizontal Parabola Horizontal Parabola
Vertical Parabola Vertical Parabola
19. HYPERBOLA
F ( focus)V
(verte
x)
A
B
A HYPERBOLA IS THE
SET OF ALL POINTS,THE
DIFFERENCE OF WHOSE
DISTANCES FROM TWO
FIXED POINTS IS
CONSTANT
V
(verte
x)
F ( focus)
20. α β
Transverse
axis
F
Conjugate axis
F(c ,0)(a ,0)( -c ,0)
(-a ,0)
O
F
F(0 ,c)
(0 ,a)
(0 ,-c)
(0 ,-a)
O
¹
¹
²
²
x² y²
a² b²
— —- = 1
-
y² x²
a² b²
— —- = 1
When 0 ≤ β < α; the plane cuts through both the nappes & the
curves of intersection is a hyperbola