1. Created by Mr. Lafferty Maths Dept.
The Circle
Area of a circle
Fractional area of a circle
Exam Type Questions
21-May-19
Created by Mr. Lafferty Maths Dept.

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

3. 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, 21 May 2019
Created by Mr Lafferty

4. 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, 21 May 2019
Created by Mr Lafferty

5. 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, 21 May 2019
Created by Mr Lafferty

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

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

8. Circle Now Try TJ N5 Lifeskills Ex 17.1 Ch17 (page 155)

9. Created by Mr. Lafferty Maths Dept.
Starter Questions 4
21-May-19
Created by Mr. Lafferty Maths Dept.

10. 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.
21-May-19
Created by Mr. Lafferty Maths Dept.

11. Fractional Area A = ½Πr² A = ½Π(10)² A = 157cm²
Find the area for the semi-circle shape ?
Solution
A = ½Πr²
180o
A = ½Π(10)²
A = 157cm²
Tuesday, 21 May 2019
Created by Mr Lafferty

12. Fractional Area A = ¼Πr² A = ¼Π(8)² A = 50.27cm²
Q. Find the area of the shape below ?
Solution
8cm
A = ¼Πr²
90o
A = ¼Π(8)²
A = 50.27cm²
Tuesday, 21 May 2019
Created by Mr Lafferty

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
21-May-19
Created by Mr. Lafferty Maths Dept.

14. Created by Mr. Lafferty Maths Dept.
Composite Area
Example : Find the area of the red part.
Area = Big Circle – Small Circle
4cm
10cm
21-May-19
Created by Mr. Lafferty Maths Dept.

15. 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
21-May-19
Created by Mr. Lafferty Maths Dept.

16. Have you updated your Learning Log ?
Circle
Now Try
TJ N5 Lifeskills
Ex 17.2
Ch17 (page 157)
Are you on Target ?
I can ?

25. 3 marks