Class 7 Maths

# Solid Shapes

• Shapes with three dimensions are called solid shapes.
• The corners of a solid shape are called its vertices. The line segments are called edges and flat surfaces are called faces.
• A skeleton outline of a solid that can be folded to make the solid is called a net of that solid. A particular solid can have many types of nets.
• An oblique sketch of a solid does not show proportional lengths. An isometric sketch shows proportional measurements of a solid. It is drawn on an isometric dot paper.
• Different sections of a solid can be viewed in many ways.
• It can be done by cutting or slicing the shape. This would show the cross-section of the solid.
• It can be done by observing 2-D shadow of a 3-D shape.
• It can be done by looking at the shape from different angles; like front view, side view and top view.

## Exercise 15.1

Question 1: Identify the nets which can be used to make cubes.      Answer: (ii), (iii), (iv) and (vi)

Question 2: Dice are cubes with dots on each face. Opposite faces of a die always have a total of seven dots on them. Insert suitable numbers in the blanks, remembering that the number on the opposite face should total to 7.    Question 3: Can this be a net for a die? Explain your answer. Answer: No, because 4 is opposite 1 and 3 is opposite 6 and they do not add up to 7.

Question 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?   (a) (1) (b) (2) (c) (3) (d) (4) 