The general standard equation for a circle with radius r centered at (h, k) is:
[tex](x-h)^2+(y-k)^2=r^2[/tex]
In this problem, since the circle is centered at the origin, the point (h, k) is (0, 0). So, substituting it:
[tex]\begin{gathered} (x-0)^2+(y-0)^2=r^2 \\ or \\ x^2+y^2=r^2 \end{gathered}[/tex]
Now, it is only necessary to find the radius. It is given in the picture (x-axis) and it has a value of 8.
So, the equation is:
[tex]\begin{gathered} (x-0)^2+(y-0)^2=8^2 \\ or\text{ } \\ (x)^2+(y)^2=8^2 \end{gathered}[/tex]
