Question

How to write an equation in standard form for a circle of other radius 3 centered at the origin

Answer 1

`from \: general \: equation \\ {x}^(2) + {y}^(2) + 2gx + 2fy + c = 0 \\ at \: the \: origin \: \: g = 0 \: and \: f = 0 \\since \: c = {g}^(2) + {f}^(2) + {r}^(2) \\ whe re \: r \: is \: radius \\ therefore \: c = {3}^(2) = 9 \\ = > {x}^(2) + {y}^(2) + 9 = 0`

Answer 2

What is the diameter of a circle if the radius is 3