Grade 7

Grade 7MensurationPerimeter and Area


Area of a Parallelogram


The concept of area in geometry helps us determine the size of a surface. In simple terms, it is the two-dimensional space that a shape occupies. Just like we measure the length of a line segment using units like centimeters or inches, similarly, we measure the area of any shape in square units, like square centimetre, square metre, etc.

In this explanation, we will learn in detail about the area of a parallelogram. We will also see how it is calculated using both formulas and examples. We will break down this concept into understandable parts, as well as basic mathematical. We will also give some examples using calculations. We will also use diagrams to help make the concept clear.

Understanding parallelograms

A parallelogram is a four-sided shape (quadrilateral) where opposite sides are parallel and equal in length. Opposite angles are equal, and adjacent angles are supplementary (i.e. their sum is 180 degrees). A rectangle and a rhombuses are special types of parallelograms, where all angles are right angles (90 degrees) or all sides are equal respectively.

Here is a simplified diagram of a parallelogram:

B B A A

In the diagram above, a represents the height (h) of the parallelogram, and b represents the base (b). The area of a parallelogram is easily calculated using the formula:

Area = Base × Height

Detailed description of the formula

Let's take a deeper look at the parallelogram area formula and understand why it works. Consider a parallelogram with base 'b' and height 'h'. Base 'b' is the horizontal side of the parallelogram. Height 'h' is the perpendicular distance between the base and its opposite side.

To understand why the formula works, imagine creating a rectangle by cutting off a triangle from one side of the parallelogram and moving it to the other side. The area of this rectangle is the same as the area of the original parallelogram, which is why the rectangle. The formula for the area of a rectangle (Area = length × width) can be adapted for a parallelogram.

H B

Finding the area of a parallelogram: examples

Let us consider some examples to understand how to calculate area using the above formula.

Example 1

Consider a parallelogram whose base is 10 cm and height 5 cm. What is its area?

Area = Base × Height Area = 10 cm × 5 cm Area = 50 cm²

Thus, the area of the parallelogram is 50 square centimeters.

Example 2

The base of a parallelogram is 7 meters and the height is 3 meters. Calculate the area.

Area = Base × Height Area = 7 m × 3 m Area = 21 m²

The area of the parallelogram is 21 square meters.

Example 3

If the base of a parallelogram is 15 inches and the height is 4 inches, what is the area?

Area = Base × Height Area = 15 in × 4 in Area = 60 in²

The area of the parallelogram is 60 square inches.

Effect of changing dimensions

It is important to see what effect will happen to the area of the parallelogram if we change either the base or the height and keep the other constant.

Changing the base

If only the base of the parallelogram is increased or decreased then the area will be affected proportionately.

For example, consider a parallelogram with a constant height of 5 cm:

  • If the base is 6 cm, then Area = 6 cm × 5 cm = 30 cm²
  • If the base is increased to 12 cm, Area = 12 cm × 5 cm = 60 cm²
  • If the base is decreased to 3 cm, Area = 3 cm × 5 cm = 15 cm²

As we can see, the area increases linearly with the base.

Changing height

If only the altitude is changed the effect on the area will be linear with respect to altitude.

For example, with a fixed base of 10 cm:

  • If the height is 4 cm, then Area = 10 cm × 4 cm = 40 cm²
  • If the height is increased to 8 cm, Area = 10 cm × 8 cm = 80 cm²
  • If the height is decreased by 2 cm, Area = 10 cm × 2 cm = 20 cm²

We see that with change in height there is a direct change in area also.

Why is it important to understand the area of a parallelogram?

The concept of area calculation is important in various fields such as construction, architecture, land measurement and even making crafts or art. Knowing how to find the area of a parallelogram helps determine how much material is needed for construction. what is needed, how much land is available for use, etc.

Understanding these concepts in school lays the groundwork for more complex geometric and mathematical problems in higher education. It also develops spatial awareness and problem-solving skills.

Conclusion

The area of a parallelogram can be easily calculated using the formula Area = Base × Height. This simple but powerful formula allows us to determine the shape of parallelograms, whether they are parts of buildings, objects, or mathematical puzzles. With the fundamentals in place, learning how to find the area of a parallelogram opens the door to further exploration in geometry and its myriad uses in the real world.

Remember, the area formula for a parallelogram is incredibly versatile and applies as long as you know its base and height. Practice calculating using different values and looking at a diagram of a parallelogram. Make sure this will help you understand how changing dimensions changes the area.

As you progress in your studies, you'll be able to see how these principles extend to more complex shapes such as trapezoids and other polygons. Understanding the basic shapes well is the first step to mastering geometry, which the subject is rich in logical reasoning and spatial visualization.


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