Question

A circle in the XY-plane has center (5, 7) and radius 2. Which of the following is an equation of the circle?

Answer 1

Answer: A, because the equation of a circle is $(x-h)^2+(y-k)^2=r^2$. So, if the point of the center is $(5,7)$ and the radius $2$ , then on the equation should be changed as negative and the radius should be multiplied as $4$, which is $(x-5)^2+(y-7)^2=4$