GeoGebra Classroom

# Union and intersection of closed intervals

## Objective

Student should be able to find the union and intersection of two closed intervals.

## Introduction

Union of two sets: A set formed by taking all elements from sets A and B without repetition is called union of sets A and B and denoted by AB. Intersection of two sets: A set formed by taking only common elements of sets A and B is called intersection of sets A and B and denoted by AB. Closed Interval: A set of all real numbers between a and b including both a and b is called closed interval of a and b, denoted by [a,b].

## Guidelines

1. move slider b, c and d randomly however you want, see what happens in the graph, where are the foots of red and green arrows. after doing this activities for few minutes 2. click on the check box A=[b,a] and B=[c,d]. just see the common portion of red and green shaded portion. then you can move slider b,c and d randomly. 3. After doing above activities, u can see A intersection B and AUB. click on box of m, n , p and q, delete the number and type the required number using the applet. if your ans is correct, there will be seen congratulation.. if congratulation is not seen, you have to do the activities on the applet seriously. 4. Finally, you have to tick the answer of the given question.