Circles - Finding area and circumference

The circumference and area of a circle can be found if the radius or diameter are known. The formulas can be extended to find arc lengths and sector areas then beyond to more complex problems. This video is to help you do the online, self-marking exercise which can be found here:

4:22 - Level 1 - find the circumference given the radius or diameter.

8:24 - Level 2 - find the radius or diameter given the circumference.

13:32 - Level 3 - find the area of a circle given either the radius or diameter.

17:51 - Level 4 - the areas of circles are given, find either the radius, diameter or circumference.

19:39 - Level 5 - the radius and angle subtended at the centre of the circle are given, find the length of the arc or area of the sector of the circle.

24:48 - Level 6 - this level has mixed questions about the circle. Most of these questions will require a multi-part calculation once the situation described in the question has been understood.