Page 12 - Mathematics Class - XII

ACTIVITY 1.2

OBJECTIVE

To verify that the relation R in the set A of all lines in a plane, defined by R = {(l, m): l || m} is an equivalence
relation.

MATERIAL REQUIRED

Y A piece of plywood or board
Y Some pieces of yarn or thread

Y Glue
Y Nails
Y Board pins
Y White paper

PRE-REQUISITE KNOWLEDGE
1. Knowledge of equivalence relations.
2. Knowledge of properties of parallel and perpendicular lines.

PROCEDURE
1. Take a piece of plywood or board of convenient size and paste a white paper on it as shown in Fig. (a).

2. Fix some board pins randomly on the plywood or board as shown in Fig. (b).

Fig. (a) Fig. (b)

3. Now take some pieces of yarn or thread and tie them with the help of nails such that some of them are
parallel, some are perpendicular to each other and some are inclined as shown in Fig. (c).

l l
2 1
l 3
l 4
l 5
l
6
l
l 7
8
Fig. (c)
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