Grade 6 → Mensuration ↓
Area
Measurement is a branch of mathematics that deals with the measurement of geometric shapes and their parameters such as length, area, and volume. A key concept in measurement is "area." Area is important to understand as it helps determine how much space a two-dimensional shape occupies. In this detailed explanation, we will understand the concept of area in great detail.
What is the area?
Area is a measure of the amount of space inside a two-dimensional boundary. It is measured in square units such as square metres (m²), square centimetres (cm²), square inches (in²), etc. In simple terms, if you think of placing a shape on a flat surface, the area will be the number of square tiles needed to completely cover that shape without gaps or overlaps.
Basic formula for area
The formula to calculate the area depends on the type of shape. Area can be calculated using different formulas depending on the geometric shape.
Area of a rectangle
A rectangle is a four-sided polygon with opposite sides equal and each angle 90 degrees. To find the area of a rectangle, you multiply its length by its width.
Area = Length × Width
For example, if a rectangle has a length of 8 m and a width of 5 m, then its area is:
Area = 8m × 5m = 40m²
Area of a square
A square is a special type of rectangle, with all sides of equal length. To find the area of a square, you need to multiply the length of one side by itself.
Area = Side × Side
So, if the length of the side of a square is 4 m, then its area will be:
Area = 4m × 4m = 16m²
Area of a triangle
A triangle is a three-sided polygon. If the base and height of the triangle are known, its area can be found using the following formula:
Area = (Base × Height) / 2
For example, if the base of a triangle is 6 m and the height is 4 m, then its area is:
Area = (6m × 4m) / 2 = 12m²
Area of a circle
A circle is a circular figure in which all the points on its edge are the same distance from the center. The area of a circle is calculated using the radius, which is the distance from the center to the edge of the circle.
Area = π × Radius²
If the radius of a circle is 3 m, then its area is:
Area = π × (3m)² = 28.27m² (approx)
Here, π (pi) is a constant that is approximately equal to 3.14159.
Visual field
Visualization helps to understand how different shapes occupy space. When visualizing area, you can think of drawing small unit squares over the shape. Count how many unit squares fill the shape completely. This count tells you the area of the shape.
Real-life examples of the field
Understanding fields is important not only in mathematics, but also in real-life applications. Let's look at some common examples:
Example 1: Floor space
Let's say you are planning to buy a carpet for your living room. You need to know the area of the floor to ensure that the carpet fits perfectly. If the room is rectangular, measure the length and width of the room to calculate the area.
Length = 5m, Width = 4m, Area = 5m × 4m = 20m²
So, you need a carpet covering an area of 20 square metres.
Example 2: Gardening
Let's say you're planting a new grass lawn and want to buy enough seed to cover the entire area. Calculate the area of your yard. If the yard is L-shaped, divide it into rectangles or triangles, find the area of each section and add them together.
Exploring complex shapes
The formulas for the basic shapes we have discussed are straightforward. However, not all shapes are standard, and we may find more complex shapes that require a combination of methods or breaking down the shape into simpler parts.
Disassembled shapes
Complex shapes can often be decomposed into a combination of rectangles, squares, triangles, or circles. Calculate the area for each component and sum them to get the total area.
Example 3: Mixed shapes
Suppose you have a garden in the shape of L. This L shape can be divided into two rectangles.
For a garden having one rectangle measuring 6 m by 3 m and the other measuring 4 m by 2 m, the area is given by:
Rectangle A: Area = 6m × 3m = 18m²
Rectangle B: Area = 4m × 2m = 8m²
Total area = 18m² + 8m² = 26m²
Units of measurement
Area is usually measured in square units. Choosing the appropriate units is important in both mathematical problems and practical applications.
Common units of area
- square millimeter (mm²)
- Square centimetre (cm²)
- Square metre (m²)
- square kilometer (km²)
- square inch (in²)
- Square foot (ft²)
- Square yard (yd²)
- Square mile (mi²)
Converting units
Conversion between different units of area may be necessary. It is important to know the relationship between these units:
1 m² = 10,000 cm² 1 cm² = 100 mm² 1 km² = 1,000,000 m² 1 m² = 1.196 yd² 1 in² = 6.452 cm²
Practice problems
To make sure you understand the concept of area, try these practice problems:
Problem 1: Find the area of a rectangle
The length of a rectangle is 12 cm and width 7 cm. Find its area.
Area = 12cm × 7cm = 84cm²
Problem 2: Find the area of the triangle
The base of a triangle is 10 m and the height is 5 m. What is its area?
Area = (10m × 5m) / 2 = 25m²
Problem 3: Determine the area of a composite figure
A figure consists of a rectangle measuring 8 cm by 3 cm and a square of side 4 cm. What is the total area?
Rectangle Area = 8cm × 3cm = 24cm² Square Area = 4cm × 4cm = 16cm² Total Area = 24cm² + 16cm² = 40cm²
Conclusion
The concept of area is foundational in understanding how two-dimensional spaces can be measured. Whether in an academic setting or in everyday life, knowing how to calculate area helps in a variety of practical scenarios such as flooring, painting, farming, and more. Mastery of calculating areas for standard geometric shapes, the ability to decompose complex shapes, and an understanding of units and conversions form the backbone of this key measurement topic.