Question 192403
x^2+9y^2=1
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(x^2/1) + (y^2/(1/9) = 1
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The center is at (0,0)
a = 1 ; b = 1/3
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a^2 = b^2+c^2
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1 = (1/9) + c^2
c = sqrt(8/9) = (2/3)sqrt(2)
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foci: ((2/3)sqrt(2),0) , ((-2/3)sqrt(2) , 0)

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Cheers,
Stan H.