Answer: The required equation of the circle is 
Step-by-step explanation: We are given to find the equation of a circle with center at the origin and radius of length 8 units.
We know that
the equation of a circle with center at the point (g, h) and radius of length r units is given by

Here,
center, (g, h) = (0, 0) and radius, r = 8 units.
Therefore, the equation of the circle will be

Thus, the required equation of the circle is 