In the previous examples, we used the standard form equation of a parabola to calculate the locations of its key features. We can also use the calculations in reverse to write an equation for a parabola when given its key features.
Given its focus and directrix, write the equation for a parabola in standard form.
Determine whether the axis of symmetry is the
x - or
y -axis.
If the given coordinates of the focus have the form
then the axis of symmetry is the
x -axis. Use the standard form
If the given coordinates of the focus have the form
then the axis of symmetry is the
y -axis. Use the standard form
Multiply
Substitute the value from Step 2 into the equation determined in Step 1.
Writing the equation of a parabola in standard form given its focus and directrix
What is the equation for the
parabola with
focus
and
directrix
The focus has the form
so the equation will have the form
Graphing parabolas with vertices not at the origin
Like other graphs we’ve worked with, the graph of a parabola can be translated. If a parabola is translated
units horizontally and
units vertically, the vertex will be
This translation results in the standard form of the equation we saw previously with
replaced by
and
replaced by
To graph parabolas with a vertex
other than the origin, we use the standard form
for parabolas that have an axis of symmetry parallel to the
x -axis, and
for parabolas that have an axis of symmetry parallel to the
y -axis. These standard forms are given below, along with their general graphs and key features.
Standard forms of parabolas with vertex (
h ,
k )
[link] and
[link] summarize the standard features of parabolas with a vertex at a point
Axis of Symmetry
Equation
Focus
Directrix
Endpoints of Latus Rectum
Questions & Answers
Biology is a branch of Natural science which deals/About living Organism.
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things