Question

What is the equation of a circle, centred at the origin (the point `(0,0)`), with a radius of `2` `units`?

Answer 1

The equation of a circle with origin `(a,b)` and radius `c` is:

`(x-a)^2 +(y-b)^2 = c^2`

In this case, `a=b=0`, and `c=2`, so the equation is:

`x^2+y^2=4`