1. Circles

2. Circle: the set of points ( x , y ) that are
equidistant from a fixed point called the
centre of the circle.
Radius: the distance between the centre of
the circle and any point ( x , y ) on
the circle

3. y
x

4. Equation of a circle with centre at the origin:

5. y
Equation?
x

6. Equation for parabola:
What does "h" do to the standard parabola?
What does "k" do to the standard parabola?

7. The standard form for equation of a circle:
where ( h, k ) is the centre and r is the radius

8. Second form for circle equation:
where d, e, and f are real numbers and
completing the square of this equation will
convert it into standard form.

9. Convert to standard form then graph:

10. y
x

11. Exercise 21
Questions 1 ­ 7