-2.4.27 find center and radius of circle

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  • Thread starter karush
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  • #1
karush
Gold Member
MHB
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Determine the graph of $x^2+y^2+6x+8y+9=0$
$\begin{array}{rll}
\textsf{rewrite} &(x^2+6x )+(y^2+8y)=-9\\
\textsf{complete square} &(x^2+6x+9)+(y^2+8y+16)=-9+9+16\\
\textsf{simplify equation} &(x+3)^2+(y+4)^2=16=4^2\\
\textsf{observation} &C(-3,-4), \quad R=4
\end{array}$

hopefully ok
is there another way to do this other than complete the square

if you are inclined to do so I would be interested in a tikz code would be fore this :unsure:
 

Answers and Replies

  • #2
skeeter
1,104
1
this is ok

completing the square is probably the most efficient technique ...

Not saying there is no other method, but I'm not familiar with any.
 
  • #3
karush
Gold Member
MHB
3,267
4
Mahalo
often when post here an alternative is suggested...
:cool:
 

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