Compare the given equation with the general equation of a circle
Given equation: x² + y² - 8x +6y +9 = 0
Equation of a circle: x² + y² + 2gx + 2fy + c = 0
2g= -8; g = -8÷2= -4
2f = 6; f = 6÷2 = 3
c= 9
Solving for radius of the circle...
r =√g² + f² - c
g= -4, g² = ±16
f = 3, f² = 9
Substituting, we have
r = √16 + 9 - 9
r = √25-9
r=√16
r = 4
Therefore, the centre and radius of the circle is 9 and 4 respectively.
Hope this helped!
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