Features Of Circles – Area and Circumference (8)

Investigate the relationship between features of circles such as circumference, area, radius and diameter. Use formulas to solve problems involving circumference and area (ACMMG197)

LO:To investigate the features of circles such as circumference, area, radius and diameter.

Know:

  • the properties and features of circles

Understand:

  • That formulas can be used to quickly find the features (area and circumference) of a circle.

Do:

  • I can find features of a circle.

Features of Circles

Diameter of a Circle

A diameter of a circle is the distance from one side of a circle to the other side of a circle. It splits a circle into 2 equal pieces.

Radius of a Circle

A radius of a circle is the distance from the center of the circle to the edge.


Circumference of a Circle

Circumference is the perimeter of a circle or the distance around the outside of the circle

Formulas for Finding Features of Circles

Formula for finding the Circumference of a circle.

There are 2 formulas for finding the circumference of a circle, they both work out to give you the same answer:

C = ∏ x d
Circumference = Pi x diameter

C = 2 x ∏ x r
Circumference = Pi x radius


Area of a Circle

Area of a circle is the amount of space that the inside of the circle occupies.

Formula for finding the area of a circle:

A = ∏ x r x r
Area = Pi x r (squared)

Features of Circles Videos

Circle Quiz

Circle Quiz

What is the area of a circle with a radius of 8 cm?

  • About 200 cm squared
  • About 2000 cm squared
  • About 50 cm squared

What is the circumference of a circle with a radius of 10 cm?

  • About 300 cm
  • About 20 cm
  • About 60 cm

What is the name of the perimeter of a circle?

  • Pi
  • Circumference
  • Diameter

A line that cuts a circle perfectly into two equal pieces is called the?

  • Diameter
  • Radius
  • Circumference

If the diameter of a circle is 10 cm, then the radius must be?

  • 5 cm
  • 20 cm
  • 10 cm

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