Topic notes and worked questions
Geometry & Mensuration
Geometry questions become much safer when you label the diagram, choose the correct dimensions and write the units at every stage.
Area of a trapezium
Use the two parallel sides and perpendicular height — and understand the formula.
Sector area and arc length
Use the angle as a fraction of a full circle and keep radius vs diameter straight.
Volume of a cylinder
Build volume from circular base area × perpendicular height and check cubic units.
Before you calculate
Underline what the question gives you and what it actually asks for. Many errors happen before the arithmetic starts.
After you calculate
Look at the size and sign of the answer. A ten-second sense check can catch a wrong setup.
When units appear
Keep them beside the numbers. Converting early is often safer than trying to repair units at the end.