Summary
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 sum of all the outer side lengths of combined shapes. Example: Total Length = L1 + L2 + L3 + L4 + L5 + L6.
- Perimeter of a Circle — Also known as the circumference, it is the length around the circle. Example: Circumference (C) = 2πr, where 'r' is the radius.
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 perimeter with area.
- 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 or use 2 x (Length + Breadth).
- What is the formula for the circumference of a circle? Circumference = 2πr.
- How do you find the perimeter of a composite figure? Add up all the outer side lengths.
What Examiners Usually Test
- Understanding of perimeter formulas for different shapes.
- Ability to apply formulas to solve problems.
- Differentiating between perimeter and area.