Question

I need help in not sure how to write a standard equation :(

Answer 1

Look at your picture

notice the coordinates for the center of the circle, the x,y or h,k values
notice how long the radius is

thus $\bf \qquad \textit{equation of a circle} \\\\\\ (x-{{ h}})^2+(y-{{ k}})^2={{ r}}^2 \qquad center\ ({{ h}},{{ k}})\qquad radius={{ r}}$