1. 1 Circle Formulae 2 The area of a circle Tandi Clausen-May Click the mouse

2. 2 Click the mouse only when you see or If you click too soon you will miss the best bits. Click the mouse Click to see Click the mouse

3. 3 The area of a circle Tandi Clausen-May Click the mouse

4. 4 We saw in Circle Formulae 1 that… Circumference =  × Diameter Now, what about the area?

5. 5 Imagine a circle made out of strands of beads. Open it out. Click the mouse Click to see the circle open

6. 6 circumference radius (half the diameter) Let’s watch that again. It’s a triangle! base = circumference Click to see the circle open again height = radius (half the diameter) Click the mouse

7. 7 circumference radius (half the diameter) = Circumference × Radius 2 Area of the triangle circle Area of the triangle We know how to find the area of a triangle. Click the mouse = Base × Height 2

8. 8 = Circumference × Radius 2 Area Summary Click the mouse

9. 9 The End Tandi Clausen-May