Relations
Chapter Name : Relations And Functions |
Sub Topic Code : 104_11_02_03_01 |
Topic Name : Relations |
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Sub Topic Name : Relations |
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Introduction
A set containing all possible combinations whose first element is from set 1 and other element is from set 2 is known as Cartesian product of the sets.
Pre-Requisites:
Idea about ordered pairs and the Cartesian product of sets.
Activity:
How many number of different meals from a given number of different items like meats, salads, vegetables, and drinks can be supplied?
Real Life Question:
As you know Brother and Sister, Father and Son, Teacher and Student are all relations. Similarly 2,3 being prime factors of 12 is also a relation!
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Relation | A relation R from a non-empty set A to a non-empty set B is a subset of the Cartesian product A X B. |
| Domain | The set of all first elements of the ordered pairs in a relation R from set A to a set B. |
| Range | The set of all second elements of the ordered pairs in a relation R from set A to a set B. |
| Co-domain | The whole set B is called the co-domain of relation R. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|
Real life uses :
Relations are used to solve equations in two variables in reverse order. Transform functions to real world data.
Places to visit :
Math Lab.
Practical examples around us
| Examples | Explainations |
|---|---|
| 1. Calendar. | Weeks as one set (Rows) and weekdays (Columns) as another set, a set with a particular week and weekday gives the date (cell resulting due to the intersection of a particular row with a particular column). |
What you learn in Theory:
What are relations? What is the domain and range of a relation?
What you learn in Practice:
How to draw relations and find relationship between two sets.