Question

Write the equation of a circle that has a center at the origin and a radius with a length of 3 inches.

Answer 1

hello : 
an equation of the circle Center at the A(a,b) and ridus : r is :
(x-a)² +(y-b)² = r²
in this exercice : a = 0 and b = 0   and r=3 (Center at the origin:  A=O)is : x²+y² = 9