Circles Lesson - GCSE

Circles

Working out area and circumfrence

Multiple Choice

Warm Up

If we are looking at length, area and then volume which of these answers has the units in the correct order?

• cm, cm³, cm²

• cm³, cm², cm

• cm, cm², cm³

Multiple Choice

Which part of the circle is the arrow pointing to?

• Arc

• radius

• Diameter

• Circumference

Multiple Choice

Which part of the circle is the arrow pointing to?

• chord

• arc

• middle

• radius

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 Answer: Circumference of Circle with Radius of 3CM

•  $\pi=3.14\ \$  Circumference is  $2\pi r\ \ or\ \ \pi d$   

• Radius is 3 so this is 2 x 3.14 x 3

• 2 x 3.14 x 3 = 18.84cm

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Answer: Area of Circle with Radius of 3CM

•  $\pi=3.14\ \$  Area is  $\pi r^2$   

• Radius is 3 so this is  3.14 x  $3^2$  

• =  3.14 x 9 = 28.26  $cm^2$  

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Answer: Volume of Cylinder with Radius 5cm 

and height 10cm

•  $\pi=3.14\ \$  Area is  $\pi r^2$   Volume is Area x height

• Radius is 5 so this is  3.14 x  $5^2$  

• Area =  3.14 x 25 = 78.5  $cm^2$  

• Volume is Area x Height = 78.5 x 10

• = 785  $cm^3$  

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