Area of a circle

The Maths Habit

Work out each circumference to 1 decimal place.

  1. A circle has a diameter of 9.5 m.

    29.8 m

  2. A circle has a radius of 7 cm.

    44.0 cm

  3. A round mirror is 30 mm across, through its centre.

    94.2 mm

Which gives you more pizza:
one 18 inch or two 12 inch?

One 18 inch

Radius
From the centre to the edge.
Diameter
All the way across, through the centre.
Area
The space inside a shape.

A = π × r2

Work out the area to 1 decimal place.

A = π × r2
A = π × 122 = 452.4 cm2
Answer452.4 cm2
A = π × r2
A = π × 152 = 706.9 cm2
Answer706.9 cm2
A = π × r2
A = π × 122 = 452.4 cm2
Answer452.4 cm2
A = π × r2
A = π × 6.52 = 132.7 cm2
Answer132.7 cm2
A = π × r2
A = π × 122 = 452.4 cm2
Answer452.4 cm2
A = π × r2
A = π × 82 = 201.1 mm2
Answer201.1 mm2
A = π × r2
A = π × 122 = 452.4 cm2
Answer452.4 cm2
A = π × r2
r = 22 ÷ 2 = 11 m
A = π × 112 = 380.1 m2
Answer380.1 m2
A = π × r2
A = π × 122 = 452.4 cm2
Answer452.4 cm2
A = π × r2
A = π × 4.22 = 55.4 cm2
Answer55.4 cm2

Work out the area to 1 decimal place.

Circumference and area of a circle worksheet, page 1

Circumference and area of a circle worksheet, page 2

Answer sheet

  1. A circle is cut from a square of side 10 cm so that it just fits inside. How much of the square is left?

    21.5 cm2

  2. A circle has an area of 200 cm2. Work out its radius to 1 decimal place.

    8.0 cm

Which gives you more pizza:
one 18 inch or two 12 inch?

One 18 inch

254.5 square inches against 226.2

  1. Find the area to 1 decimal place.

    50.3 cm2
    4 cm

  2. Find the area to 1 decimal place.

    153.9 m2
    14 m

  3. A circle has a diameter of 20 cm. Kai says its area is 1256.6 cm². Is Kai right? Explain.

    No, r = 10: 314.2 cm2
Exit tickets to print