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.

**Answer:**

**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?

**Answer:**

**Question 5:** Match the nets with appropriate solids.

Column I | Column II |
---|---|

(a) | (1) |

(b) | (2) |

(c) | (3) |

(d) | (4) |

**Answer:** (a) → 2, (b) → 3, (c) → 4, (d) → 1

Fractions

Data Handling

Simple Equations

Lines & Angles

Properties of Triangles

Congruence of Triangles

Comparing Quantities

Rational Numbers

Geometry Construction

Perimeter Area

Algebraic Expressions

Exponents & Powers

Symmetry

Solid Shapes