Ask: linear, square or cubic? Then compare the size with the diagram.
Key formulas
Unit family
cm vs cm² vs cm³. Writing cm for an area is an easy mark lost.
Scale sense
A triangle inside a 10 cm square should not have area 800 cm². If it does, a decimal slipped.
Angle sense
An angle in a triangle larger than 180° is impossible. Recheck the calculator mode and the identity used.
Worked example
Worked example
Problem. A student finds a triangle area as 24 cm and a tank volume as 2.4 m. Correct the units.
Solution. Area must be cm² (or m²). Volume must be m³ (or convert 2.4 m³ = 2400 L if capacity in litres was intended). Rewrite: 24 cm² and 2.4 m³.
Litres
1 m³ = 1000 litres — convert only at the end.
Review quiz
Volume of a tank should be reported in:
Practice questions
- Name one impossible answer for a triangle angle.
- Convert 2500 cm³ to litres.
Study notes
Exact or decimal?
Keep exact surds/π until the question asks to round.