Question

2. Write the equation of the circle with a center at

(-2, -8) and a radius of v10.

A. (x + 2)^2 + (y + 8)^2 = 25
B. (x - 2)^2 + (y – 8)^2 = 10
C. (x + 2)^2 + (y + 8)^2 = 10
D. (x + 2)^2 + (y + 8)^2 = 100
E. (x - 2)^2 + (y - 3)^2 = 100

Answer 1

C.
`(x +2) ^2 +(y+8)^2 =10`

Explanation:

Center of the circle (h, k) = (-2, - 8)

Radius
`r=\sqrt {10}`

Equation of circle in center radius form is given as:

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

Plugging the values of h, k and r in the above equation, we find:

`[x - (- 2)] ^2 +[y-(-8) ]^2 =(\sqrt {10})^2`

`(x +2) ^2 +(y+8)^2 =10`