## RD Sharma Class 8 Solutions Chapter 19 - Visualising Shapes (Ex 19.2) Exercise 19.2 - Free PDF

## FAQs on RD Sharma Class 8 Solutions Chapter 19 - Visualising Shapes (Ex 19.2) Exercise 19.2

**1.What are two dimensional and three-dimensional objects discussed in chapter 19 class 8 CBSE maths?**

2D and 3D shapes are discussed in geometry to mention differences between various objects we see every day. Figures were drawn on a flat plane surface, which has only two measurements like length, breadth and height are called 2D objects. For example, a triangle is a 2D object.

On the other hand, a geometrical figure drawn with three different measurements like length, breadth and height are called 3D objects. For example, a prism might look like a triangle but with 3 dimensions. A circle is a 2D object whereas a sphere is a 3D object. 2D shapes are surrounded by lines and segments whereas 3D objects are surrounded by surfaces. Area and perimeter are measured for 2D objects whereas surface area is measured for 3D objects.

**2. What is the difference between a solid and a hollow solid as mentioned in chapter 19 class 8 CBSE maths?**

Geometry deals with solids and hollow solids. Solids are 3D objects framed when more than two two-dimensional geometrical figures are piled up on each other. For example, putting more than two circles above each other vertically forms a cylindrical shape. On the other hand, hollow solids are formed by joining two-dimensional figures. For example, a hollow cuboid is formed when six rectangles are joined together, one on each surface. A hollow cube is formed similarly when 6 squares are joined together. A hollow triangular prism is formed when two triangles and three rectangles are rough together.

**3. What is the area of the figure and how is it different from the volume of an object?**

Area is the place occupied by a two-dimensional figure which has length and breadth. It is measured for 2D figures whereas volume is the place occupied by three-dimensional figures which have an additional measure of the height along with length and breadth. For example, the area is measured for a rectangle which is two dimensional whereas volume is measured for a cuboid which is three dimensional. Similarly, the area is measured for a square and volume is measured for the cuboid. The area is measured for triangles and volume is measured for prisms.

**4. What is a cuboid and what is the formula to find its area and volume given in chapter 19 class 8 CBSE maths?**

Cuboid is a geometrical figure with 6 rectangular faces. It is a three-dimensional representation of a rectangle. It is a convex polyhedron that has twelve edges, eight vertices. A shoebox in real life is the best example of a cuboid. Following are the formulas to find out the area and volume for a cuboid:

The volume of a cuboid is represented by V.

V = l*b*h

l is the length, b is the breadth and h is the height of the cuboid

The perimeter of a cuboid is represented by P

P = 4(l+b+h)

The total surface area of a cuboid is represented by TSA

TSA = 2( lb+bh+hl)

Lateral surface area is represented by LSA

LSA = 2h(l+b)

**5. How to remember formulas mentioned in chapter 19 class 8 CBSE maths?**

Chapter 19 deals with shapes and figures. It is a very important chapter in geometry. Some students face difficulty in understanding this chapter as there are many shapes and formulas to remember. To avoid confusion, follow these steps:

Write down all the formulas on paper and read them every day without fail.

Try visualising the objects and comparing them with real-life objects for better understanding.

Solve as many problems as possible to improve efficiency. As soon as you see the question, try to make a rough diagram with approximate dimensional values.

Avoid mistakes while filling up values in the formula.

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