# 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.

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

## 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)

# Circle Quiz

### Circle Quiz

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

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