1. Circumference
𝑪=𝝅𝒅 𝑪=𝟐𝝅𝒓

2. Write the formula first ! Pg 176 Exercise 9b No. 13, 15, 16, 17
Homework
Write the formula first ! Pg 176 Exercise 9b No. 13, 15, 16, 17

3. Homework Check 13. Radius 154 mm 𝑪=𝟐𝝅𝒓 𝑪=𝟐×𝝅×𝒓 𝑪=𝟐×𝝅×𝟏𝟓𝟒
𝑪=𝟗𝟕𝟎 𝒎𝒎 (𝟐 𝒔.𝒇.)

4. Homework Check 15. Radius 7.7 m 𝑪=𝟐𝝅𝒓 𝑪=𝟐×𝝅×𝒓 𝑪=𝟐×𝝅×𝟕.𝟕
𝑪=𝟒𝟖 𝒎 (𝟐 𝒔.𝒇.)

5. Homework Check 16. Radius 34.6 cm 𝑪=𝟐𝝅𝒓 𝑪=𝟐×𝝅×𝒓 𝑪=𝟐×𝝅×𝟑𝟒.𝟔
𝑪=𝟐𝟐𝟎 𝒄𝒎 (𝟐 𝒔.𝒇.)

6. Homework Check 17. Diameter 511 mm 𝑪=𝝅𝒅 𝑪=𝝅×𝒅 𝑪=𝝅×𝟓𝟏𝟏
𝑪=𝟏𝟔𝟎𝟎 𝒎𝒎 (𝟐 𝒔.𝒇.)

7. Circumference
𝑪=𝝅𝒅 𝑪=𝟐𝝅𝒓

8. =𝝅𝒅 𝟑𝟕𝟔.𝟖𝟎=𝝅𝒅 𝟑𝟕𝟔.𝟖𝟎 𝝅 =𝒅 𝟏𝟏𝟗.𝟗𝟒𝒄𝒎=𝒅 Circumference
FIND THE DIAMETER of a circle with a
CIRCUMFERENCE OF CM.
WORKING:
376.80cm
Circumference
=𝝅𝒅
𝟑𝟕𝟔.𝟖𝟎=𝝅𝒅
𝟑𝟕𝟔.𝟖𝟎 𝝅 =𝒅
𝟏𝟏𝟗.𝟗𝟒𝒄𝒎=𝒅
Tuesday, November 13, 2018

9. Find the radius of a circle if its circumference is ……...
(a) cm
Answer: 4 cm
(b) m
Answer: 6 m
Round your answer to the nearest whole number!
Tuesday, November 13, 2018

10. Draw Half a Circle

11. Draw a Quarter Circle

12. 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑆𝑒𝑚𝑖−𝐶𝑖𝑟𝑐𝑙𝑒=25.1 ÷𝟐=12.6𝑐𝑚
Perimeter
Find the perimeter of this shape
8cm
𝐶=𝜋𝑑
𝐶=𝜋×8
=25.1 𝑐𝑚 (1𝑑𝑝)
𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑆𝑒𝑚𝑖−𝐶𝑖𝑟𝑐𝑙𝑒=25.1 ÷𝟐=12.6𝑐𝑚
Length of diameter = 8cm
Perimeter of shape =
= 20.6cm(1dp)

13. 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑄𝑢𝑎𝑟𝑡𝑒𝑟−𝐶𝑖𝑟𝑐𝑙𝑒
Perimeter
Find the perimeter of this shape
3cm
𝐶=2𝜋𝑟
𝐶=2×𝜋×3
=18.8 𝑐𝑚 (1𝑑𝑝)
𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑄𝑢𝑎𝑟𝑡𝑒𝑟−𝐶𝑖𝑟𝑐𝑙𝑒
=18.8 ÷𝟒=4.7 𝑐𝑚
Length of radii = 3cm + 3cm
= 6cm
Perimeter of shape=
=10.7cm(1dp)

14. 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑆𝑒𝑚𝑖−𝐶𝑖𝑟𝑐𝑙𝑒=31.4 ÷𝟐=15.7𝑐𝑚
Perimeter
Find the perimeter of this shape
𝐶=𝜋𝑑
𝐶=𝜋×10
=31.4 𝑐𝑚 (1𝑑𝑝)
3cm
𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑆𝑒𝑚𝑖−𝐶𝑖𝑟𝑐𝑙𝑒=31.4 ÷𝟐=15.7𝑐𝑚
10cm
Length of straight sides =
=16cm
Perimeter of shape =
= 31.7cm(1dp)

15. Worksheet: Finding the Perimeter