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

Fill in the Blank

What is the circumference of this Circle with radius 3cm? Use 3.14 for Pi ( $\pi$  )  in your calculation. Circumference is

 $2\pi r\ or\ \pi d$  

 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

Fill in the Blank

What is the circumference of this Circle with diameter 7cm? Use 3.14 for Pi ( $\pi$  )  in your calculation. Circumference is

 $2\pi r\ or\ \pi d$  

Fill in the Blank

What is the circumference of this Circle with diameter 5cm? Use 3.14 for Pi ( $\pi$  )  in your calculation. 

Fill in the Blank

What is the area of this Circle with radius 3cm? 

Use 3.14 for Pi ( $\pi$  )  in your calculation. 

Area is  $\pi r^2$    (just write down the numbers)

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  $cm^2$  

Fill in the Blank

What is the area of this Circle with diameter 7cm? 

Use 3.14 for Pi ( $\pi$  )  in your calculation. 

Area is  $\pi r^2$   (just write down the numbers)

Fill in the Blank

What is the area of this Circle with radius 2cm? 

Use 3.14 for Pi ( $\pi$  )  in your calculation. 

(just write down the numbers)

Fill in the Blank

What is the volume of this cylinder with radius 5cm and height 10cm? 

Use 3.14 for Pi ( $\pi$  )  in your calculation. 

(just write down the numbers)

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  $cm^3$  

Fill in the Blank

What is the volume of this cylinder with radius 6cm and height 5cm? 

Use 3.14 for Pi ( $\pi$  )  in your calculation. 

(just write down the numbers)