**Points to Remember:**Plane shapes having two measurements like length and breadth are called two dimensional shapes (2-D).

Solid shapes having three measurements like length, breadth and height or depth are called three dimensional shapes (3-D).

In polyhedron relationship between no. of faces (F), vertices (V) and edges (E) is F + V – E = 2 It is also called Euler’s Formula.

Prism : A polyhedron whose base and top are congruent polygon and whose other faces are parallelogram.

Pyramid : A polyhedron whose base is a polygon and whose lateral faces are triangles with a common vertex.

**Practice Worksheet**

**1. Write down the number of faces of each of the following figures:**

(i) Cuboid (ii) Cube (iii) Triangular prism (iv) Square pyramid (v) Tetrahedron

**2. Write down the number of edges of each of the following figures:**

(i) Tetrahedron (ii) Rectangular pyramid (iii) Cube (iv) Triangular prism

**3. Write down the number of vertices of each of the following figures:**

(i) Cuboid (ii) Square pyramid (iii) Tetrahedron (iv) Triangular prism

**4. Fill in the blanks:**

(i) A cube has …………….. vertices, …………….. edges and …………….. faces.

(ii) The point at which three faces of a figure meet is known as its …………….. .

(iii) A cuboid is also known as a rectangular …………….. .

(iv) A triangular pyramid is called a …………….. .

**Answers:**

**1.**(i) 6 (ii) 6 (iii) 5 (iv) 5 (v) 4

**2.**(i) 6 (ii) 8 (iii) 12 (iv) 9

**3.**(i) 8 (ii) 5 (iii) 4 (iv) 6

**4.**(i) 8, 12, 6 (ii) vertex (iii) prism (iv) tetrahedron