2. The midpoint of a circle is centre

3. The line drawn from the centre to the circumference is … radius

4. The line drawn from one circumference through the centre to another circumference is … radius diameter The diameter cuts the circle in half!

5. Radius and Diameter The radius is equal to half of the diameter: r= d 2 The diameter is equal to double the radius d= 2r

6. A line that connects one point on the edge of the circle with another point on the circle is called …. chord The chord that passes through the centre of the circle is the diameter.

7. The central angle is and angle that is measured using center O of a circle

8. A segment ie. part of the circumference of the circle is called an... a r c

9. Major and Minor Arcs A minor arc measures less than 180⁰ A major arc measures more than 180⁰ 360⁰ - major arc = minor arc 360⁰ - minor arc = major arc

10. Parts of the Circle centre radius diameter chord arc

11. The outside of the circle is called circumference The circumference is the distance around the circle.

12. Circumference The circumference is the perimeter of the circle. In order to calculate the circumference you need to use the irrational number ∏ (pi)

13. ∏ (pi) It is an irrational number because it never ends. We use pi to calculate the circumference and area of a circle.

14. Calculating Circumference If you divide the circumference of any circle by its diameter you will always get pi as the answer. Therefore if you multiply the diameter of any circle by pi you will always get the circumference.

15. CIRCUMFERENCE FORMULA Because the radius is double the diameter we need to multiply it by two in order to calculate the circumference.

16. AREA FORMULA