# Math Help - Radii and centre of a circle.

1. ## Radii and centre of a circle.

A level Maths.
Induction.
Write down the centre and radius of the given circle x^2+y^2=4
The general equation for a circle of radius $r$ centered at the point $(a,b)$ is $(x-a)^{2}+(y-b)^{2}=r^{2}.$ From this, can you read off the coordinates of the center, and the radius?