Perimeter and area · Grade 6

In Grade 6 you learn: area of triangles and parallelograms; area of trapezoids.

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.

Worked examples

Example 1

Find the area of this L-shape. All corners are right angles; lengths are in cm.

Answer: 55 cm²

Example 2

A triangle has a base of 10 cm and a perpendicular height of 7 cm. Find its area.

Answer: 35 cm²

Example 3

A trapezium has parallel sides of 6 cm and 10 cm and a height of 5 cm. Find its area.

Answer: 40 cm²

Other years