Question

What is the general form of the equation of a circle with its center at (-2, 1) and passing through (-4, 1)?

Answer 1

The equation of circle is:
(x-a)^2+(y-b)^2=r^2 where C(a, b) is the center.
In order to find r you have to find the distance between C(-2, 1) and let's say A(-4, 1)

The formula for distance is:
$\sqrt{ ( y_{A}-y_{C )^{2} + (x_{A}- x_{C )^{2} }$
r = 2

The equation of circle is
(x+2)^2+(y-1)^2=4

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