1. Length and Area (Quadrilaterals and Circles)
Vocabulary:
Circle
Sector
Radius
Diameter
Circumference
Tangent
Segment
chord
Parallelogram
Rhombus
Kite
perimeter
quadrant
Area
exact
approximate
Semicircle
dimensions
arc
Trapezium

2. What do you remember… How do you find the perimeter of a figure?
What is the formula for finding the area of a:
Rectangle
Square
Triangle?

3. Revision:

5. Find the area AND the perimeter of each shape:

6. Area of a parallelogram
We can find the area of a parallelogram by cutting it and rearranging the pieces:
Demonstration
So the area of a parallelogram is found using:
Area = base x height
A = b x h
= 5 x 12
= 60 cm2

8. Areas of other special Quadrilaterals

12. Challenge!

13. Properties of a Circle
A circle is defined as a set of points which is equally distant (or equidistant) from one fixed point.
The fixed point is called the centre of the circle.
The line joining the centre to the circumference is called the radius
The diameter goes through the centre, from one side of the circle to the other. It is twice as long as the radius
A chord joins any two points on the circumference. A chord divides a circle into a major segment and a minor segment

14. Labelling Activity:

15. tangent

16. Identify each feature:

17. Investigation:
Draw EIGHT different sized circles (carefully) using a pair of compasses in your book.
Use the string to measure the circumference (around the edge) and record it in a table like below.
Measure and record the diameter (distance across the circle) of each circle.
Circumference
Diameter

18. What is ?

19. Circumference of a Circle
The circumference of any circle is given by:
You use the most appropriate formula, depending on whether you know the radius or the diameter.
Who can remember the most digits of ?

21. What about parts of a circle’s circumference?
In general terms:

27. Challenge!

28. Area of a Circle
We can use what we know about the circumference of a circle to find the area of the circle…
So the area of a circle is A = r2 where r is the radius

33. Applications