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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