Study Notes
The perimeter is the total length around a 2D shape. It can be calculated differently depending on the shape.
- Perimeter of a Rectangle or Square — the total length of all four sides. Example: For a rectangle, Perimeter = Length x 2 + Breadth x 2.
- Perimeter of Composite Figures — the total length of all outer sides of combined shapes. Example: Add all side lengths together: Total Length = L1 + L2 + L3 + L4 + L5 + L6.
- Perimeter of a Circle — also known as the circumference, calculated using the radius. Example: Circumference (C) = 2πr, where π ≈ 3.14 or 22/7.
Exam Tips
Key Definitions to Remember
- Perimeter is the total length around a shape.
- Circumference is the perimeter of a circle.
Common Confusions
- Mixing up formulas for different shapes.
- Forgetting to multiply by 2 for rectangles and squares.
Typical Exam Questions
- How do you calculate the perimeter of a rectangle? Add the lengths of all sides: Length x 2 + Breadth x 2.
- What is the formula for the circumference of a circle? Circumference = 2πr.
- How do you find the perimeter of composite figures? Add all the outer side lengths together.
What Examiners Usually Test
- Correct use of formulas for different shapes.
- Understanding of how to combine side lengths in composite figures.