Page 206 - ICSE Math 8

EXERCISE 18.2

1. For each of the given 3D figures, identify the top, front and side views.
Top

(a) Side

(i) (ii) (iii)
Front

Top

Side
(b)

Front (i) (ii) (iii)

Top

Side
(c)

Front (i) (ii) (iii)

AT A GLANCE

¾ A three-dimensional shape made up of polygons is called a polyhedron.
¾ Euler’s formula: F + V = E + 2, where V, F and E stands for number of vertices, faces and edges of a
polyhedron respectively.
¾ A polyhedron whose side faces are parallelograms and bases are congruent parallel polygons is called
a prism.
¾ A pyramid is a polyhedron whose base is a polygon and whose side faces are triangles having a common
vertex called the apex.
¾ Platonic solid are regular convex polyhedra. There are only five platonic solids namely tetrahedron,
hexahedron, octahedron, icosahedron, dodecahedron.
¾ A net of a 3D figure is its outline in 2D which when folded regains its 3D shape.

¾ There are three views of a 3D shape—front, top, and side view.

MENTAL MATHS

1. Choose the correct option.
(a) The number of faces in a triangular prism are:

(i) 5 (ii) 4 (iii) 3 (iv) 2

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