Stage 9 Maths – Formula Sheet
Percentages
x% = x/100
x% of a number = (x/100) × number
Percentage = (part ÷ whole) × 100
Area & Measures
Rectangle: l × w
Square: s²
Triangle: ½ × b × h
Parallelogram: b × h
Trapezium: ½(a + b)h
Circle: πr²
Circumference: 2πr
Ratio & Proportion
a : b = a/b
Total parts = a + b
One part = total ÷ total parts
a/b = c/d → ad = bc
3D Shapes
Cube volume: s³
Cuboid volume: l × w × h
Cylinder volume: πr²h
Cube surface area: 6s²
Cuboid surface area: 2(lw + lh + wh)