Page 9 - Mathematics_Form_3

Relations

Suppose that A and B are two non-empty set B on the right hand side as shown
sets. A relation between A and B is a set in Figure 1.2. The arrows from the set
of connections that associate elements of of children connect the children to the
set A with the elements of set B according set of their aunts. For instance, Ibrahim
to a specific rule. The sets may include is a nephew of Belina, in this case, an
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people, objects or numbers. Consider the arrow is drawn from Ibrahim to Belina.
family tree in Figure 1.1 which shows This type of representation is called an
three sisters and their children. arrow diagram, a mapping diagram or
a pictorial diagram.

‘is a nephew of’
A B
Fatima
Ibrahim Fatima
Hussein Belina

Simon
Ibrahim Asha Hussein Zuhura

Figure 1.2: Pictorial representation of
the relation ‘is a nephew of’
The sets A and B in Figure 1.2 have
Belina
no elements in common. However, sets
can have elements in common. The
sets could even be the same. Figure 1.3
represents the relation ‘is a brother of’.
Beatrice Simon Neema
In this relation, sets A and B consist
of six children who are brothers and
Mathematics for Secondary Schools Shamsa Zuhura Rehema as described in Figure 1.1. Ibrahim
sisters of each other born to two sisters

‘is a brother of’

A
B

Ibrahim
Asha
Figure 1.1: Relationship between sisters
and their children
Beatrice
Simon
The relation ‘is a nephew of ’ can be Hussein Hussein
Neema
illustrated as follows; let A be a set
of children and B be a set of sisters.
Figure 1.3: Pictorial representation of
Place set A on the left hand side and the relation ‘is a brother of’

2 Student\s Book Form Three

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