Visualising Solid Shapes 15.1

Visualising Solid Shapes Full exercise on Visualising Solid Shapes, fully solved. This is a video tutorial for 7th class NCERT CBSE students. For other educational stuff, subscribe and press bell icon. INTRODUCTION: PLANE FIGURES AND SOLID SHAPES In this chapter, you will classify figures you have seen in terms of what is known as dimension. In our day to day life, we see several objects like books, balls, ice-cream cones etc., around us which have different shapes. One thing common about most of these objects is that they all have some length, breadth and height or depth. That is, they all occupy space and have three dimensions. Hence, they are called three dimensional shapes. Do you remember some of the three dimensional shapes (i.e., solid shapes) we have seen in earlier classes? FACES, EDGES AND VERTICES Do you remember the Faces, Vertices and Edges of solid shapes, which you studied earlier? Here you see them for a cube:The 8 corners of the cube are its vertices. The 12 line segments that form the skeleton of the cube are its edges. The 6 flat square surfaces that are the skin of the cube are its faces. We could also try to make a net for making a pyramid like the Great Pyramid in Giza (Egypt). That pyramid has a square base and triangles on the four sides. NETS FOR BUILDING 3-D SHAPES EXERCISE 15.1 1. Identify the nets which can be used to make cubes (cut out copies of the nets and try it): 2. Dice are cubes with dots on each face. Opposite faces of a die always have a total of seven dots on them. Here are two nets to make dice (cubes); the numbers inserted in each square indicate the number of dots in that box. Insert suitable numbers in the blanks, remembering that the number on the opposite faces should total to 7. 3. Can this be a net for a die? Explain your answer. 4. Here is an incomplete net for making a cube. Complete it in at least two different ways. Remember that a cube has six faces. How many are there in the net here? (Give two separate diagrams. If you like, you may use a squared sheet for easy manipulation.) 5. Match the nets with appropriate solids: