Nets and Surface Area

≈ 35 min

Nets and Surface Area

A net is a 3D solid opened flat. It helps you see every face exactly once. For a rectangular prism, calculate the areas of length by width, length by height and width by height, then double their sum. Use a table to avoid losing a face or counting it twice.

Worked example

A prism is 5 cm by 4 cm by 2 cm. Face areas are 20, 10 and 8. Surface area $=2(20+10+8)=76\text{ cm}^2$ .

Exam method

Sketch or label the net. 2. List matching face pairs. 3. Add their areas and use square units.

A cube has edge length 4 cm. Find its surface area in $\text{cm}^2$ .

Find the surface area of a $3\text{ cm}\times2\text{ cm}\times1\text{ cm}$ rectangular prism.

Why is a net useful when finding surface area?

It shows every outside face

It measures the volume directly

It removes the need for units

It makes all faces circular

Surface area is measured in ______ units.