Pre-Calc Notes
Name______________________Date_______
Topic: (10.2) Parabolas
Main Ideas:
Notes:
Parts of a Parabola:
a) Vertex
b) Focus
c) Directrix
d) Latus Rectum
Definition:
The set of all points equidistant
from a point (focus) as they are
from a fixed line (directix)
Different Orientations of a
Parabola:
x 2 
 Opening up or down
How do we know when it will
face up/down or left/right?
Opening Up/Down
y2 
 Opening left or right
Opening Left/Right
Vertex @ origin:
x 2  4ay
y2  4ax
The vertex to the focus
and
the vertex to the directrix.
Vertex @ (h,k):
x  h 2  4a(y  k)
y  k 2  4a(x  h)
* Positive a signifies:
* Negative a signifies:
Opening Up
Opening Down
Opening Right
Opening Left
Practice Recognizing Graphs
Turn to page 643 in your book and complete #’s 11-18.
-Things to remember:
- Is it opening up/down or left/right?
- Is a positive or negative?
- Where is the vertex?
- How does knowing the latus rectum come in handy?
*a is the distance from:
Graph the following parabolas
with the vertex at the origin.
a) y2  12x
b) x 2  8y
Graph the following parabolas
with the vertex at (h, k)
c. (x  2)2  8(y  3)
d. y2  4y  4x  4  0
Homework:
p.643 #19,21,22,30,37,39,41,43,47,48,60,61