SOLUTION: Graph the hyperbola (x+3)^2-9(y-4)^2=9 Endpoints of traverse axis? Endpoints of conjugate axis? I know how to find the center, foci and asymptotes but am confused on how to

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Graph the hyperbola (x+3)^2-9(y-4)^2=9 Endpoints of traverse axis? Endpoints of conjugate axis? I know how to find the center, foci and asymptotes but am confused on how to       Log On


   



Question 1033120: Graph the hyperbola (x+3)^2-9(y-4)^2=9
Endpoints of traverse axis?
Endpoints of conjugate axis?
I know how to find the center, foci and asymptotes but am confused on how to find the endpoints.

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!


Instead of doing yours for you, I'll do one
exactly like it, which you can use as a model:

%28%28x%2B2%29%5E2%29%2F25+-+%28%28y-7%29%5E2%29%2F64+=+1

%28%28x-h%29%5E2%29%2Fa%5E2+-+%28%28y-k%29%5E2%29%2Fb%5E2+=+1
 
h+=+-2, k=7, 
 
a%5E2=25, so a=5
 
b%5E2=64, so b=8
 
The center (h,k) = (-2,7)
 
We start out plotting the center C(h,k) = C(-2,7)
 

 
Next we draw the left semi-transverse axis,
which is a segment a=5 units long horizontally 
left from the center.  This semi-transverse
axis ends up at one of the two vertices (-7,7).
We'll call it V1(-7,7):
 

 
Next we draw the right semi-transverse axis,
which is a segment a=5 units long horizontally 
right from the center. This other semi-transverse
axis ends up at the other vertex (3,7).
We'll call it V2(3,7):
 

 
That's the whole transverse ("trans"="across",
"verse"="vertices", the line going across from
one vertex to the other. It is 2a in length,
so the length of the transverse axis is 2a=2(5)=10
 
Next we draw the upper semi-conjugate axis,
which is a segment b=8 units long verically 
upward from the center.  This semi-conjugate
axis ends up at (-2,15).
 

 
Next we draw the lower semi-conjugate axis,
which is a segment b=8 units long verically 
downward from the center.  This semi-conjugate
axis ends up at (-2,-1). 
 

 
That's the complete conjugate axis. It is 2b in length,
so the length of the transverse axis is 2b=2(8)=16
 
Next we draw the defining rectangle which has the
ends of the transverse and conjugate axes as midpoints
of its sides:
 

 
Next we draw and extend the two diagonals of this defining
rectangle:
 

 
Now we can sketch in the hyperbola:
 


The foci are points inside the hyperbola, which are the distance c
from the center, where c is calculated by

c%5E2=a%5E2%2Bb%5E2  (just like the Pythagorean theorem, from whence
it comes):

c%5E2=a%5E2%2Bb%5E2
c%5E2=5%5E2%2B8%5E2
c%5E2=25%2B64
c%5E2=89
c=sqrt%2889%29

So the two foci are sqrt%2889%29 units 
right and left of the center, which is
(h,k) = (-2,7)

Therefore the foci are:

(-2-sqrt%2889%29,7) and (-2%2Bsqrt%2889%29,7) 

They are approximately the points:

(-11.4,7) and (7.4,7).  I won't bother plotting
them.

All that's left to do is find the equations of the two asymptotes.
Their slopes are ±b%2Fa or ±8%2F5
 
The asymptote that has slope 8%2F5 goes through the center
C(-2,7), so its equation is found using the point-slope
formula:
 
y-y%5B1%5D=m%28x-x%5B1%5D%29
y-%287%29=%288%2F5%29%28x-%28-2%29%29
y-7=%288%2F5%29%28x%2B2%29
Multiply through by 5
5y-35=8%28x%2B2%29
5y-35=8x%2B16
-8x%2B5y=51
 
The asymptote that has slope -8%2F5 goes through the center
C(-2,7), so its equation is found using the point-slope
formula:
 
y-y%5B1%5D=m%28x-x%5B1%5D%29
y-%287%29=%28-8%2F5%29%28x-%28-2%29%29
y-7=%28-8%2F5%29%28x%2B2%29
Multiply through by 5
5y-35=-8%28x%2B2%29
5y-35=-8x-16
8x%2B5y=19
 -----------------------------------------------
Edwin