Perimeter, Area, and Volume

Perimeter, area, and volume questions appear on both stages of the SET 11+ maths papers. You need to know the formulas, apply them to a range of shapes, and — especially on Stage 2 — show every step of your working. This lesson covers all the key formulas and gives you plenty of worked examples.

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Perimeter

The perimeter is the total distance around the outside of a shape.

Rectangles

Perimeter = 2 × (length + width)

Example: A rectangle is 12 cm long and 7 cm wide.

• Perimeter = 2 × (12 + 7) = 2 × 19 = 38 cm

Compound Shapes

For compound (L-shaped or T-shaped) shapes, add up all the outer edges. You may need to work out missing lengths first.

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Area

Area is the amount of surface a shape covers. It is measured in square units (cm², m²).

Key Formulas