9.1. Introduction

We have learnt that for a closed plane figure, the perimeter is the distance around its boundary and its area is the region covered by it.

This chunk explains two fundamental concepts in geometry: perimeter and area. The perimeter of a closed figure is the total distance around its edges. For example, if you have a rectangle, to calculate the perimeter, you would add the lengths of all four sides. The area, on the other hand, refers to the amount of space contained within that figure. For a rectangle, the area can be calculated by multiplying its length by its width. These two concepts are crucial for understanding how to measure shapes in mathematics.

Imagine walking around a park; the distance you walk around the park's boundary is akin to the perimeter. Now, think about the grass inside the park; the amount of grass you have is like the area of the park.

We found the area and perimeter of various plane figures such as triangles, rectangles, circles etc. We have also learnt to find the area of pathways or borders in rectangular shapes.

Here, we talk about common shapes such as triangles, rectangles, and circles that we often study in geometry. For each of these shapes, there are specific formulas to find the area and perimeter. Additionally, understanding how to compute the area of pathways around these shapes, like a border around a rectangular garden, allows us to apply these concepts to real-world scenarios.

Think about a rectangular garden; to fill it with soil or plant grass, you'd need to know how much area you have to work with. If there's a stone pathway surrounding your garden, you'll use the same principles to find out the area of the pathway.

In this chapter, we will try to solve problems related to perimeter and area of other plane closed figures like quadrilaterals.

This chunk introduces quadrilaterals, which are four-sided polygons (like squares, rectangles, and trapezoids). The chapter will focus on calculating the perimeter and area of these shapes. Quadrilaterals are abundant in geometric problems, and learning how to handle them is essential for progressing in geometry.

Consider a swimming pool that is in the shape of a rectangle. To put a fence around it (perimeter) and to determine how much water it can hold (area), knowing how to deal with quadrilaterals is crucial.

We will also learn about surface area and volume of solids such as cube, cuboid and cylinder.

This chunk provides an overview of what students will learn about three-dimensional shapes. The concepts of surface area (the total area of all the outer surfaces of a solid) and volume (the amount of space within a solid) are crucial for understanding physical space. Students will discover how these shapes differ in terms of measurement from two-dimensional figures.

Think about a box of chocolates. When you want to gift it, you need to know how much wrapping paper you’ll need (surface area). When filling it, you also care about how many chocolates it can fit inside (volume).

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