Question

The equation of the circle whose center is at (3, 7) and whose radius is 6 is a. (x + 3)² + (y + 7)² = 6 b. (x + 3)² + (y + 7)² = 36 c. (x - 3)² + (y - 7)² = 36

Answer 1

$\bf \textit{equation of a circle}\\\\ (x- h)^2+(y- k)^2= r^2 \qquad center~~(\stackrel{3}{ h},\stackrel{7}{ k})\qquad \qquad radius=\stackrel{6}{ r} \\\\\\ (x-3)^2+(y-7)^2=6^2\implies (x-3)^2+(y-7)^2=36$