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Area and Perimeter

Distinguish between the space inside a shape (area) and the distance around it (perimeter), covering rectangles, triangles, and composite shapes.

Key Ideas

  • Perimeter is the total distance around the outside of a 2D shape.
  • Area is the amount of space inside a 2D shape.
  • Area of a rectangle = length × width.
  • Area of a triangle = 1/2 × base × height.
  • For composite shapes, break them down into simpler shapes (rectangles/triangles).

Worked Examples

Example 1

Find the area of a triangle with base 8cm and height 5cm.

Explanation

Identify the formula: Area = 1/2 × base × height.

Substitute the values: Area = 1/2 × 8 × 5.

Calculate: 1/2 × 40 = 20.

Include units: 20 cm².

Ready to Practice?

Test your understanding of Area and Perimeter with targeted questions from our bank.

Common Mistakes
  • ×Confusing area and perimeter formulas.
  • ×Forgetting to use square units (e.g., cm²) for area.
  • ×Using the slanted side length instead of the perpendicular height for triangles.
Exam Tip

"Trace the perimeter with your finger to make sure you don't miss any sides, especially on 'L' shaped polygons."