Perimeter and area · Year 10
In Year 10 you learn: sectors and composite shapes.
Perimeter is the distance all the way round a shape; area is the amount of flat space it covers, measured in square units. Knowing the area formulas for rectangles, triangles, parallelograms and trapeziums lets you work out compound shapes too.
Key facts
- Rectangle: area = length × width; perimeter = 2 × (length + width).
- Triangle: area = ½ × base × perpendicular height.
- Parallelogram: area = base × perpendicular height.
- Trapezium: area = ½ × (a + b) × h, where a and b are the parallel sides.
- Compound shapes: split into rectangles (or subtract a missing piece). Use the same units throughout.