Question

How do I find the radius of a circle with a center at (-1, -2), which also passes through point (0,2)?

Answer 1

\[(x-x_c)^2+(y-y_c)^2=r^2\\center=(-1,-2)\\so\\(x+1)^2+(y+2)^2=r^2\\\]
the circle passes through (0,2)

so check the point in equation
to find r


can you go on ?

Answer 2

@amoodarya I'm still a little confused. Could you explain further?

Answer 3

The previous post used the standard form of a circle at center (h ,k)
Let h=xc let k= yc
then you have a point (0,2)

(0,2)
(x+1)^2 + (y+2)^2 = r^2
(0+1)^2 + (2+2)^2 = r^2
1+4 = r^2
5= r^2
\[r=\sqrt{5}\]

Answer 4

Ok. Thanks