SOLUTION: find the equation of a circle with radius 5 and centered at (3,-1)? thanks!!!

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Question 146717: find the equation of a circle with radius 5 and centered at (3,-1)? thanks!!!
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Using the equation %28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2 we can see that h=3, k=-1 and r=5. So the equation is %28x-3%29%5E2%2B%28y-%28-1%29%29%5E2=5%5E2 which simplifies to %28x-3%29%5E2%2B%28y%2B1%29%5E2=25


Now we need to expand and simplify %28x-3%29%5E2%2B%28y%2B1%29%5E2=25

%28x-3%29%5E2%2B%28y%2B1%29%5E2=25 Start with the given equation


x%5E2-6x%2B9%2B%28y%2B1%29%5E2=25 Foil %28x-3%29%5E2 to get x%5E2-6x%2B9


x%5E2-6x%2B9%2By%5E2%2B2y%2B1=25 Foil %28y%2B1%29%5E2 to get y%5E2%2B2y%2B1


x%5E2-6x%2B9%2By%5E2%2B2y%2B1-25=0 Subtract 25 from both sides


x%5E2%2By%5E2-6x%2B2y-15=0 Combine like terms



So the equation is x%5E2%2By%5E2-6x%2B2y-15=0