Question

What is the center of the circle represented by this equation? x2 + (y + 9)2 = 25

A) (3, 5) B) (0, 25) C) (9, 25) D) (0, -9)

Answer 1

`\bf \textit{equation of a circle}\\\\ (x- h)^2+(y- k)^2= r^2 \qquad center~~(\stackrel{}{ h},\stackrel{}{ k})\qquad \qquad radius=\stackrel{}{ r}\\\\ -------------------------------\\\\ x^2+(y+9)^2=25\implies [x-\stackrel{h}{0}]^2+[y-\stackrel{k}{(-9)}]^2=\stackrel{r}{5^2}\qquad \qquad \quad \stackrel{center}{(0,-9)}`