Perimeter and area of rectangles, triangles, parallelograms and trapeziums, L-shapes from a diagram, and changing between cm² and m².
What you will learn
- Find the perimeter and area of a rectangle
- Use ½ × base × height and the parallelogram and trapezium formulas
- Split a compound shape into rectangles
- Convert between cm², m² and mm²
Perimeter goes round, area fills in
The perimeter is the distance all the way round the edge, in cm or m: add every side.
A rectangle 6 m by 2.5 m has perimeter 6 + 2.5 + 6 + 2.5 = 17 m. The area is the space inside, in cm² or m².
rectangle: area = length × width
triangle: area = ½ × base × perpendicular height
parallelogram: area = base × perpendicular height
trapezium: area = ½ × (a + b) × h
In the trapezium, a and b are the two parallel sides and h is the distance between them.
Not drawn accurately
- area = ½ × (4 + 9) × 3
- = ½ × 13 × 3
- = 19.5 cm²
The rest of this lesson and its 8 practice questions are locked.
In this lesson
- Perimeter goes round, area fills in
- The height must be perpendicular
- Area units are squared
- Try it: An easy one first
8 practice questions, marked as you go; about 25 minutes in all.
Key terms
Perimeter, Area, Parallel, Right angle
In this unit: Area, perimeter and volume
Perimeter and area of rectangles, triangles, parallelograms, trapeziums and compound shapes, circles, arcs and sectors, and the volume and surface area of prisms, cylinders, pyramids, cones and spheres.