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Finding the Equation of a Circle in the Coordinate Plane

1) Find the equation of a circle with radius = 10 and center (6, -3).

2) Find the radius and center of a circle with the equation $x^{2}+y^{2}=4$ .

1) general form: $(x-h)^{2}+(y-k)^{2}=r^{2}$ , radius = r, center = (h, k)

r = 10

h = 6

k = -3

$(x-6)^{2}+(y--3)^{2}=10^{2}$

$(x-6)^{2}+(y+3)^{2}=100$

2) $x^{2}+y^{2}=4$

$(x-0)^{2}+(y-0)^{2}=4$

$r^{2}=4$
$\sqrt{r^2}=4$

$r=2$

$center=(0,0)$