One to one maths interventions built for KS4 success

Weekly online one to one GCSE maths revision lessons now available

In order to access this I need to be confident with:

2D shapes/polygons

RoundingMultiplication and division

Substituting numbers into formulae Converting between metric units BIDMASThis topic is relevant for:

Here we will learn how to work out area.

There are also how to work out area* *worksheets based on Edexcel, AQA and OCR exam questions, along with further guidance on where to go next if you’re still stuck.

**Area **is a measure of how much space there is inside of a 2 dimensional shape. To find the area of a shape we can either count the number of unit squares within the shape or use the appropriate area formula for that shape.

Area is measured in square units e.g. cm^{2}, \; m^{2}, \; mm^{2} .

The table below shows the formulae for calculating area for some of the most common 2 D shapes:

In order to work out area:

**Write down the formula.****Substitute the values into the formula.****Do the calculation.****Write the answer, including the units.**

Get your free how to work out area worksheet of 20+ questions and answers. Includes reasoning and applied questions.

DOWNLOAD FREEGet your free how to work out area worksheet of 20+ questions and answers. Includes reasoning and applied questions.

DOWNLOAD FREE**How to work out area** is part of our series of lessons to support revision on **area**. You may find it helpful to start with the main area lesson for a summary of what to expect, or use the step by step guides below for further detail on individual topics. Other lessons in this series include:

Work out the area of the rectangle

**Write down the formula.**

2**Substitute the values into the formula.**

Here the base is 11cm and the height is 4cm.

Area=11 \times 43**Do the calculation.**

4**Write the answer, including the units.**

The measurements are in centimetres so the area will be measured in square centimetres.

Area=44cm^2Work out the area of the parallelogram

**Write down the formula.**

Area= base \times height

**Substitute the values into the formula.**

Here the base is 10m and the height is 6m.

Area=10 \times 6

**Do the calculation.**

Area=10 \times 6

Area=60

**Write the answer, including the units.**

The measurements are in metres so the area will be measured in square metres.

Area=60m^2

Calculate the area of the rhombus

**Write down the formula.**

\text{Area }=\frac{1}{2} \times \text{ width } \times \text{ height}

or \text{Area }= \frac{1}{2} \times \text{ diagonal } \times \text{ diagonal}

**Substitute the values into the formula.**

Here the width is 20mm and the height is 8mm.

\text{Area }=\frac{1}{2} \times 20 \times 8

**Do the calculation.**

\begin{aligned}
\text{Area }&=\frac{1}{2} \times 20 \times 8\\\\
\text{Area }&=80
\end{aligned}

**Write the answer, including the units.**

The measurements are in millimetres so the area will be measured in square millimetres.

Area=80mm^2

Find the area of the trapezium

**Write down the formula.**

\text{Area }=\frac{1}{2}(a+b)h

**Substitute the values into the formula.**

In a trapezium, a and b are the parallel sides and h is the height.

Here a=3, \; b=5 and h=4

\text{Area }=\frac{1}{2}(3+5) \times 4

**Do the calculation.**

\begin{aligned}
&\text{Area }=\frac{1}{2}(3+5) \times 4\\\\
&\text{Area }=\frac{1}{2} \times 8 \times 4\\\\
&\text{Area }=16
\end{aligned}

**Write the answer, including the units.**

The measurements are in cm so the area will be measured in cm^2 .

Area=16cm^2

Work out the area of the triangle

**Write down the formula.**

\text{Area }=\frac{1}{2} \times \text{ base } \times \text{ height}

**Substitute the values into the formula.**

Since this is a right triangle, we can see the base of the triangle is 13mm and the height of the triangle is 6mm .

\text{Area }=\frac{1}{2} \times 13 \times 6

**Do the calculation.**

\begin{aligned}
\text{Area }&=\frac{1}{2} \times 13 \times 6\\\\
\text{Area }&=39
\end{aligned}

**Write the answer, including the units.**

The measurements are in mm so the area will be measured in mm^2 .

Area=39mm^2

Work out the area of the circle. Give your answer to 1 decimal place

**Write down the formula.**

\text{Area }=\pi r^{2}

**Substitute the values into the formula.**

Here the radius, r, is 3.5cm .

\text{Area }=\pi \times 3.5^{2}

**Do the calculation.**

\begin{aligned}
\text{Area }&=\pi \times 3.5^{2}\\\\
\text{Area }&=38.48451001
\end{aligned}

**Write the answer, including the units.**

We need to write the answer to one decimal place and include the units.

Area=38.5cm^2

In order to work out area of a compound shape:

**Draw lines to split the shape into two or more smaller shapes. Label the shapes A, B, C, …****Consider each shape individually.****a)****Work out any measurements that you need.****b) Calculate the area using the methods above.****Add or subtract the relevant areas to find the total area.****Write the answer, including the units.**

Work out the area of the following shape

**Draw lines to split the shape into two or more smaller shapes. Label the shapes A, B, C, …**

**Consider each shape individually.**

Shape A

**a) Work out any measurements that you need.**

For a rectangle, we need the height and the base,both of which we are given.

**b) Calculate the area using the methods above.**

\begin{aligned} \text{Area }&=\text{ base }\times \text{ height}\\\\ &=10 \times 6\\\\ &=60\mathrm{cm}^{2} \end{aligned}

Shape B

**a) Work out any measurements that you need.**

For a trapezium, we need a, \; b and h.

**b) Calculate the area using the methods above.**

\begin{aligned}
\text{Area }&=\frac{1}{2}(a+b)h\\\\
&=\frac{1}{2}(5+10) \times 3\\\\
&=22.5\mathrm{cm}^{2}
\end{aligned}

**Add or subtract the relevant areas to find the total area.**

Total area: 60+22.5=82.5

**Write the answer, including the units.**

\text{Area } =82.5cm^2

Work out the shaded area. Give your answer to one decimal place.

**Draw lines to split the shape into two or more smaller shapes. Label the shapes A, B, C, …**

The shape is already clearly split.

**Consider each shape individually.**

Shape A

**a) Work out any measurements that you need.**

For a triangle we need the height and base, which we are given

**b) Calculate the area using the methods above.**

\begin{aligned}
\text{Area }&= \frac{1}{2} \times \text{ base } \times \text{ height}\\\\
&=\frac{1}{2} \times 10 \times 14\\\\
&=70\mathrm{cm}^{2}
\end{aligned}

Shape B

**a) Work out any measurements that you need.**

Here we need the radius of the circle, which is 3.2cm

**b) Calculate the area using the methods above.**

\begin{aligned}
\text{Area }&=\pi \times r^{2}\\\\
&=\pi \times 3.2^{2}\\\\
&=32.16990877\\\\
&=32.17\mathrm{cm}^{2}
\end{aligned}

**Add or subtract the relevant areas to find the total area.**

Shaded area: 70-32.17=37.83

**Write the answer, including the units.**

\text{Area } =37.8cm^2

**Using an incorrect formula**

There are several different formulae for the different shapes – make sure you use the correct one.

**Using the incorrect units/not including units**

Area is measured in square units.

E.g.

Square millimetres, square centimetres, square metres, square inches, square feet, square yards etc.

**Calculating with different units**

All measurements must be in the same units before calculating surface area.

E.g.

You can’t have some measurements in cm and some in m.

**Calculating perimeter/circumference instead of area**

Remember, perimeter is distance around the outside whilst area is the space inside the shape.

**Using diameter instead of radius for a circle**

To work out the area of a circle we need the radius, which is the distance from the centre of the circle to the edge of the circle.

1. Work out the area of the square

14\mathrm{cm}^{2}

49\mathrm{cm}^{2}

28\mathrm{cm}^{2}

42\mathrm{cm}^{2}

Since this is a square, the base and height are the same, 7cm.

\begin{aligned} \text{Area }&=\text{ base } \times \text{ height}\\\\ &=7 \times 7\\\\ &=49\mathrm{cm}^{2} \end{aligned}

2. Work out the area of the parallelogram

55\mathrm{mm}^{2}

18\mathrm{mm}^{2}

36\mathrm{mm}^{2}

77\mathrm{mm}^{2}

The base is 11mm and the height is 5mm.

\begin{aligned} \text{Area }&=\text{ base } \times \text{ height }\\\\ &=11 \times 5\\\\ &=55\mathrm{mm}^{2} \end{aligned}

3. Calculate the area of the rhombus

260\mathrm{m}^{2}

33\mathrm{m}^{2}

16.5\mathrm{m}^{2}

130\mathrm{m}^{2}

\begin{aligned}
\text{Area }&=\frac{1}{2} \times \text{ width } \times \text{ height}\\\\
&=\frac{1}{2} \times 20 \times 13\\\\
&=130\mathrm{m}^{2}
\end{aligned}

4. Find the area of the trapezium

36\mathrm{cm}^{2}

60\mathrm{cm}^{2}

26\mathrm{cm}^{2}

576\mathrm{cm}^{2}

\begin{aligned}
\text{Area }&=\frac{1}{2}(a+b)h\\\\
&=\frac{1}{2} (8+12) \times 6\\\\
&=60\mathrm{cm}^{2}
\end{aligned}

5. Work out the area of the triangle

36\mathrm{mm}^{2}

13\mathrm{mm}^{2}

18\mathrm{mm}^{2}

72\mathrm{mm}^{2}

\begin{aligned}
\text{Area }&=\frac{1}{2} \times \text{ base } \times \text{ height}\\\\
&=\frac{1}{2} \times 9 \times 4\\\\
&=18\mathrm{mm}^{2}
\end{aligned}

6. Calculate the area of the circle. Give your answer to 3sf.

69.1\mathrm{m}^{2}

1520\mathrm{m}^{2}

34.6\mathrm{m}^{2}

380\mathrm{m}^{2}

\begin{aligned}
\text{Area }&=\pi r^{2}\\\\
&=\pi \times 11^{2}\\\\
&=380.132711\\\\
&=380\mathrm{m}^{2}
\end{aligned}

7. Work out the area of the compound shape

418\mathrm{cm}^{2}

550\mathrm{cm}^{2}

561\mathrm{cm}^{2}

286\mathrm{cm}^{2}

Shape A:

\begin{aligned} \text{Area }&=\frac{1}{2} \times \text{ base } \times \text{ height}\\\\ &=\frac{1}{2} \times 22 \times 12\\\\ &=132\mathrm{cm}^{2} \end{aligned}

Shape B:

\begin{aligned} \text{Area }&=\text{ base } \times { height}\\\\ &=22 \times 13\\\\ &=286\mathrm{cm}^{2} \end{aligned}

Total area: 132+286=418cm^2

1. Work out the area of this shape

**(3 marks)**

Show answer

\text{Area of trapezium: }\frac{1}{2}(6+14) \times 8=80\mathrm{cm}^{2}

**(1)**

**(1)**

Total area: 80 + 77 = 157cm^2

**(1)**

2. Sean wants to paint both sides of a fence which is 20m long and 1.5m high.

One tin of the paint that Sean wants to use will cover 15m^2 . How many tins of paint should Sean buy?

**(3 marks)**

Show answer

\text{Area of one side: } 20 \times 1.5 = 30\mathrm{m}^{2}

**(1)**

**(1)**

60 \div 15 = 4 tins

**(1)**

3. A shop sells pizza in two sizes: 10 inches and 13 inches. Would Louise get more pizza if she bought one large pizza or two small pizzas? Show how you decide.

**(3 marks)**

Show answer

\text{Small pizza: Area }=\pi \times 5^{2} = 78.54\text{ square inches}

\text{Two small pizzas: } 2\times 78.54=157.08 \text{ square inches}

**(1)**

\text{Large pizza: Area} = \pi \times 6.5^{2} = 132.72 \text{ square inches}

**(1)**

Two small pizzas

**(1)**

You have now learned how to:

- Work out the area of triangles, quadrilaterals and circles
- Work out the area of compound shapes

Prepare your KS4 students for maths GCSEs success with Third Space Learning. Weekly online one to one GCSE maths revision lessons delivered by expert maths tutors.

Find out more about our GCSE maths revision programme.

x
#### FREE GCSE maths practice papers (Edexcel, AQA & OCR)

Download free

8 sets of free exam practice papers written by maths teachers and examiners for Edexcel, AQA and OCR.

Each set of exam papers contains the three papers that your students will expect to find in their GCSE mathematics exam.