Question

Given a circle with a center (0,-5) and a radius of 2, what is the equation of the circle?

a. x^2 + (y-5)^2 =4

b. (x-5)^2 + y^2 =4

c. X^2 + (y +5)^2 = 4

Answer 1

The equation of a circle:

`(x-h)^2+(y-k)^2=r^2`

(h, k) - a coordinates of the center

r - a radius

We have:

`(0,-5)\to h=0;\ k=-5\\r=2`

substitute

`(x-0)^2+(y-(-5))^2=2^2\\\\x^2+(y+5)^2=4`

Answer: c. x^2 + (y +5)^2 = 4