Question

help please!!! Geometry!
How do i do this?!

Equations of Circles

Find the equation of the circle with the given center and radius.

C(0, 0), r = 4
A) (x + 4)2 + (y + 4)2 = 4
B) x2 + y2 = 4
C) x2 + y2 = 16
D) (x - 2)2 + (y - 2)2 = 16

Answer 1

C

Answer 2

C

Answer 3

thank u but how did u get that answer?

Find the equation of the circle with the given center and radius.

C(2, -1); r = 3
A) (x + 2)2 + (y - 1)2 = 3
B) (x - 2)2 + (y + 1)2 = 9
C) (x + 2)2 + (y - 1)2 = 9
D) (x - 2)2 + (y + 1)2 = 3

Answer 4

The equation of a circle is (x-xc)^2 + (y-yc)^2 = r^2
where (xc,yc) are the coordinates of the center and r is the radius.

Replace to verify that it is C

Answer 5

\[(x-h)^2+(y-k)^2=r^2\] is general equation for circle with center (h,k) radius r

Answer 6

in your case you have
\[h=2,k=-1,r=9\] so you get
\[(x-2)^2+(y+1)^2=9\]

Answer 7

sorry i meant
\[h=2,k=-1,r=3\]

Answer 8

oh so 2 is A?!

Answer 9

I get a little thank u...