The equation of a circle with centre
and radius
is
or![]()
This equation is a consequence of Pythagoras theorem and is illustrated below.

The equation of a circle is a quadratic equation because of the
and
terms.
The equation of a circle with centre
and radius
is
or![]()
This equation is a consequence of Pythagoras theorem and is illustrated below.

The equation of a circle is a quadratic equation because of the
and
terms.