Summary
The area is the amount of space a shape occupies in a two-dimensional plane. It can be calculated using specific formulas for different shapes.
- Area of a Rectangle — calculated by multiplying the length by the breadth. Example: If a rectangle has a length of 5 cm and a breadth of 3 cm, its area is 15 cm².
- Area of a Square — calculated by multiplying the length by itself. Example: If a square has a side length of 4 cm, its area is 16 cm².
- Area of a Composite Figure — found by breaking the figure into rectangles or squares and summing their areas. Example: A shape made of two rectangles with areas of 10 cm² and 15 cm² has a total area of 25 cm².
- Area of a Circle — calculated using the formula πr², where r is the radius. Example: A circle with a radius of 3 cm has an area of approximately 28.26 cm².
- Area of a Triangle — calculated as 1/2 x base x perpendicular height. Example: A triangle with a base of 6 cm and height of 4 cm has an area of 12 cm².
- Area of a Parallelogram — calculated as base x perpendicular height. Example: A parallelogram with a base of 5 cm and height of 3 cm has an area of 15 cm².
- Area of a Trapezium — calculated as 1/2 x (sum of two parallel sides) x perpendicular height. Example: A trapezium with parallel sides of 4 cm and 6 cm, and height of 3 cm, has an area of 15 cm².
- Area of a Prism or Cylinder — calculated as the sum of the areas of the bases and the curved surface. Example: A cylinder with a radius of 2 cm and height of 5 cm has an area of approximately 87.92 cm².
Exam Tips
Key Definitions to Remember
- Area of a Rectangle = Length x Breadth
- Area of a Square = Length x Length
- Area of a Circle = πr²
- Area of a Triangle = 1/2 x Base x Height
- Area of a Parallelogram = Base x Height
- Area of a Trapezium = 1/2 x (Sum of two parallel sides) x Height
- Area of a Prism or Cylinder = 2 x Base Area + Curved Surface Area
Common Confusions
- Confusing the formulas for the area of a rectangle and a square.
- Mixing up the radius and diameter in the circle area formula.
Typical Exam Questions
- What is the area of a rectangle with a length of 8 cm and a breadth of 3 cm? Answer: 24 cm²
- How do you find the area of a circle with a radius of 5 cm? Answer: Use the formula πr², which gives approximately 78.5 cm²
- Calculate the area of a triangle with a base of 10 cm and a height of 6 cm. Answer: 30 cm²
What Examiners Usually Test
- Ability to apply the correct formula for different shapes.
- Understanding of how to decompose composite figures into simpler shapes.
- Accuracy in calculations involving π and square units.