1. Created by Mr. Lafferty Maths Dept.
The Circle
Area of a circle
Fractions of a circle
7-May-19
Created by Mr. Lafferty Maths Dept.

2. Created by Mr. Lafferty Maths Dept.
Starter Questions 6 5
7-May-19
Created by Mr. Lafferty Maths Dept.

3. Area of a Circle www.mathsrevision.com
Peeling an
orange A
circumference A B x x O O
What do we call the distance OA in terms of
the large circle.
What do we call the distance AB in terms of the large circle.

4. Created by Mr. Lafferty Maths Dept.
Area of a Circle O A x B
What is the formula for the area
of a right-angle triangle.
Use this formula to work out
the area for a circle.
7-May-19
Created by Mr. Lafferty Maths Dept.

5. And lay them out side by side
Area of a Circle
If we break the circle
into equal sectors
And lay them out side by side
We get very close
to a rectangle. 1 2 3 4 5 6 7 8 4 5 6 7 8 2 3 1
Demo
Tuesday, 07 May 2019
Created by Mr Lafferty

6. Area of a Circle www.mathsrevision.com 8 2 4 6 3 1 5 7
If we cut the sectors
Thinner and thinner then
we get closer and closer
to a rectangle. Hence we can represent the area of a circle
by a rectangle. 1 2 3 4 5 6 7 8
thinner and thinner
sectors
Tuesday, 07 May 2019
Created by Mr Lafferty

7. Area = πr2 Area of a Circle www.mathsrevision.com
But the area inside this rectangle is also the area of the circle
Area = πr2
Tuesday, 07 May 2019
Created by Mr Lafferty

8. Created by Mr. Lafferty Maths Dept.
Area of a circle
Q. Find the area of the circle ?
Solution
4cm
7-May-19
Created by Mr. Lafferty Maths Dept.

9. Created by Mr. Lafferty Maths Dept.
Area of a circle
The diameter of the circle is 60cm.
Find area of the circle?
Solution
7-May-19
Created by Mr. Lafferty Maths Dept.

10. Created by Mr. Lafferty Maths Department
Area
Now try TJ3a
Ex 1
Ch14 (page 126)
7-May-19
Created by Mr. Lafferty Maths Department

11. Created by Mr. Lafferty Maths Dept.
Starter Questions 4
7-May-19
Created by Mr. Lafferty Maths Dept.

12. Created by Mr. Lafferty Maths Dept.
Mixed Problems
The Circle
Learning Intention
Success Criteria
1. We are learning to solve problems by applying our knowledge of circles.
Recall knowledge of circles so far.
2. Solve mixed problems by applying all our knowledge so far.
7-May-19
Created by Mr. Lafferty Maths Dept.

13. Created by Mr. Lafferty Maths Dept.
Mixed Problems
The Circle
Example 1 : Find the area of the shape
Area = rectangle + semicircle
20cm
5 cm
7-May-19
Created by Mr. Lafferty Maths Dept.

14. Created by Mr. Lafferty Maths Dept.
Mixed Problems
The Circle
Example 2 : A circle is contained in a square.
Find the grey shaded area below.
8cm
Area = square - circle
7-May-19
Created by Mr. Lafferty Maths Dept.

15. Area Now try TJ3a Ex 2 Ch14 (page 128) www.mathsrevision.com
Have you updated your Learning Log ?
Area
Now try TJ3a
Ex 2
Ch14 (page 128)
Are you on Target ?
I can ?
7-May-19
Created by Mr. Lafferty Maths Department