Riding the equation of a circle centered at the origin given it’s radius or appoint on the circle

The equation of a circle with center (h, k) and radius r is given by,
[tex](x-h)^2+(y-k)^2=r^2[/tex]Given,
Center = (0, 0)
So, h = 0, k = 0
Radius = 7
So, r = 7
Now, we can write the equation:
[tex]\begin{gathered} (x-h)^2+(y-k)^2=r^2 \\ x^2+y^2=7^2 \\ or \\ x^2+y^2=49 \end{gathered}[/tex]Answer[tex]x^2+y^2=49[/tex]