Answer:
[tex]x^2+y^2=16[/tex]
Step-by-step explanation:
The equation of a circle with center (h,k) and radius r is given by the formula;
[tex](x-h)^2+(y-k)^2=r^2[/tex]
Given (h,k)=(0,0) and r=4, we substitute the values to obtain;
[tex](x-0)^2+(y-0)^2=4^2[/tex]
The required equation is
[tex]x^2+y^2=16[/tex]