10% of a number is 20
What is that number
Write the ratio 5:10
in the form 1 : n
Do Now
11/01/2023
Factorise
𝟕𝒙 + 𝟏𝟒
Solve to find 𝒙
𝟒𝒙 + 𝟐 = 𝟏𝟎
What is the formula
of the area of a
trapezium
Expand
𝟓(𝟑𝒙 + 𝟓)
RECAP
The circumference is the distance all the way around a circle
π
(Pi)
about
circles
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that Think
lineastraightened
out-the
this is
the circumference
Think
line around
outside
of a circle
The Circumference
People noticed that if you divide the circumference of a circle by the
diameter you ALWAYS get the same answer
They called the answer Pi (π) , which is:
3.1415926535897932384626433832795028841971693993751
058209749445923078164062862089986280348253421170679
821480865132823066470938446095505822317253594081284
You can use the
8111745028410270193852110555964462294895493038196
π button on your
442881097566593344612847564823378678316527120190914
calculator
5648566923460348610454326648213393607260249141273
724587006606315588174881520920962829254091715364367
892590360011330530548820466521384146951941511609...
Circumference of a circle
To calculate the circumference of a circle, the
distance around a circle, we simply do this;
Circumference = π x diameter
How to remember......
Cherry pies taste delicious!
C=πxd
Finding the Circumference
You can find the circumference of a circle by using the formula-
Circumference = π x diameter
For Example10cm
Area= π x 10
= 31.41592654....
= 31.4 cm (to 1 dp)
I DO
Finding the Circumference
You can find the circumference of a circle by using the formula-
Circumference = π x diameter
For Example3cm
Area= π x 6
= 18.849555....
= 18.8 cm (to 1 dp)
I DO
WE DO
Finding the Circumference
You can find the circumference of a circle by using the formula-
Circumference = π x diameter
For Example4cm
Area= π x 8
= 25.132741....
= 25.1 cm (to 1 dp)
You can find the circumference of a circle by using the formula-
Circumference = π x diameter
For Example-
10cm
Area= π x 10
= 31.41592654....
= 31.4 cm (to 1 dp)
Find the Circumference of a circles with:
1. A diameter of :
a) 8cm
b) 4cm
c) 11cm
d) 21cm
e) 15cm
2. A radius of :
a) 6cm
b) 32cm
c) 18cm
d) 24cm
e) 50cm
YOU DO
Area of a circle
Area is the space inside a shape. We can calculate
the area in a circle by doing this;
Area = π x radius2
How to remember......
Apple pies are too!
A = πr²
Finding the Area
You can find the area of a circle by using the formula-
Area= π x Radius2
For Example7cm
Area= π x 72
= π x 49
= 153.93804
= 153.9 (to 1dp) cm2
I DO
Finding the Area
You can find the area of a circle by using the formula-
Area= π x Radius2
For Example10cm
Area= π x 52
= π x 25
= 78.5398163…
= 78.5 (to 1dp) cm2
WE DO
Finding the Area
You can find the area of a circle by using the formula-
Area= π x Radius2
7cm
YOU DO
For ExampleArea= π x 72
= π x 49
= 153.93804
= 153.9 (to 1dp) cm2
Real life example
Circumference of a circle
Try to calculate the circumference of a
basketball hoop.
Circumference = π x diameter
= π x 46cm
Circumference = 144.44cm
46cm
Real Life example
Circumference & Area
Calculate the Area &
Circumference of
a football pitch
centre circle?
18 metres
Circumference
Circumference = π x diameter
= π x 18m
= 56.52 m
Area
Area = π x radius2
= π x 92
= 254.34 m2
Real Life example
Calculate the Area
& Circumference
the London Eye?
60 metres
Circumference
Circumference = π x diameter
= π x 120m
= 376.8. m
Area
Area = π x radius2
= π x 602
= 11304 m2