SOLUTION: How do I write thte equation of a circle with the center at (-2,2) and a radius of 4?

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Question 91183: How do I write thte equation of a circle with the center at (-2,2) and a radius of 4?
Answer by praseenakos@yahoo.com(507) About Me  (Show Source):
You can put this solution on YOUR website!
Question:

equation of a circle with the center at (-2,2) and a radius of 4?
Answer:

The general equation of a circle whose centre is(a,b) and radius r is given by,
+%28x-a%29%5E2+%2B+%28x-b%29%5E2+=+r%5E2+

So here the equation is given by......

+%28x-%28-2%29%29%5E2+%2B+%28x-2%29%5E2+=+4%5E2+

+%28x%2B2%29%5E2+%2B+%28x-2%29%5E2+=+16+, which is the equation of the given circle...

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You can expand this expression as follows.


==> +x%5E2+%2B+4x+%2B+4+%2B+x%5E2+-+4x+%2B+4+=+16+


==> +x%5E2+%2B+x%5E2+%2B+4x+-+4x+++%2B+4+%2B+4+=+16+


==> +2x%5E2+%2B+8+=+16+

==> +2x%5E2+%2B+8+-+16+=+0+


==> +2x%5E2+-+8+=+0+

==> +x%5E2+-+4+=+0+

==> ( x+ 2 ) ( x - 2 ) = 0, which is the simplified form the equation of the given circle.


Hope you understood.

Regards.

Praseena.