The equation of a circle is x^2+y^2+18x+4y+49=0. What are the center and the radius of the circle?

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Respuesta :

Answer:

Center: (-9, -2)

Radius = 6

Step-by-step explanation:

The general equation of the circle is:

[tex]x^{2} + y^{2}+2gx+2fy+c=0[/tex]

The center of the circle is given as (-g, -f) and the radius of this circle is calculated as:

[tex]r=\sqrt{g^{2}+f^{2}-c}[/tex]

The given equation is:

[tex]x^{2} +y^{2}+18x+4y+49=0[/tex]

Re-writing this equation in a form similar to general form:

[tex]x^{2} +y^{2}+2(9)(x)+2(2)(y)+49=0[/tex]

Comparing this equation with general equation we get:

g = 9

f = 2

c = 49

Thus center of the given circle is (-g, -f) = (-9, -2)

The radius of the circle will be:

[tex]r=\sqrt{9^{2}+2^{2}-49}=6[/tex]

Thus the radius of the given circle is 6.