Exercise 46 Page 786

Let's start by recalling the standard form of an equation of a circle. (x- h)^2+(y- k)^2= r^2 In this form, ( h, k) is the center of the circle and r is its radius. We are told that the center of the circle is at the origin, so its coordinates are ( 0, 0). We also know that the radius is 3. This information is enough to write the equation. (x- 0)^2+(y- 0)^2= 3^2 ⇕ x^2+y^2=9