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Find the radius of the circle with equation x^2 - 4x + y^2 - 6y - 36 = 14x + 2y

 Sep 28, 2021
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 x^2 - 4x + y^2 - 6y - 36 = 14x + 2y     simplfy

x^2 -18x       +  y^2 -8y        = 36          'complete the square' for x and y

(x-9)^2         +  (y-4)^2         = 36 + 81 + 16

                                          = 133 = r^2                   r = sqrt (133)

 Sep 29, 2021

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