class 4 maths chapter 1

 

                           MATHEMATICS

                           ENGLISH MEDIUM

 

        4

                                                    FOURTH STANDARD

                                                  PART-1

                                                 CHAPTER-1

                                                 Perimeter And Area Of Simple

                                                Geometrical Figures

Chapter - 1

Perimeter and area of simple geometrical figures

The sum of length of all the sides of a geometrical figure is called its perimeter.

Exercise:  1.1

       I.                                                       Find the perimeter of following geometrical figures.

                       1.

 

 

Ans:   given EF=3CM, FG=5CM, GH=7CM,

 HI=5CM, IE=4CM.

Perimeter    =    EF + FG + GH + HI + IE

=   3CM + 5CM + 7CM + 5CM + 4CM

=   24CM

                    2.

 

Ans:  given JK=8CM, KL=6CM, LM=6CM,

MN=5CM, NJ=2CM.

Perimeter   =   JK + KL + LM + MN + NJ

=   8CM + 6CM + 6CM + 5CM + 2CM

=   27CM

                     3.

 

Ans:  given PQ=4CM, QR=2CM, RS=2CM,

ST=4CM, TU=3CM, UP=3CM.

Perimeter   =   PQ + QR + RS + ST + TU + UP

=   4CM + 2CM + 2CM + 4CM + 3CM +3CM

=   18CM

                   4.

Ans:  given WX=7CM, XC=8CM, CN=4CM,

NR=6CM, RM=3CM, MW=2CM.

Perimeter   =   WX + XC + CN + NR + RM + MW

=   7CM + 8CM + 4CM + 6CM + 3CM + 2CM

=   30CM

 

 

     II.                                           In list ‘A’ plane figure and in list ‘B’ their perimeter are given.

                           Match list ‘A’ with list ‘B’:

                      

                           A                                        B                           Answer

 

                   1.

            

                                                               a)  20cm                      e) 18cm                     

2.                                              b)15cm                         a)20cm

 

                   3.

                     c)        24cm                      b)15cm

              4.

                     d)      22cm                           c)24cm                                               

 

 

e)      18cm

 

 

Exercise 1. 2

 

          1.        

 

 

 

Observe the given figure. If its perimeter is 24 cm,

then what is the length of the fourth side (QS)?

Ans: Perimeter = 24cm

PQ=10CM, RS= 10CM, PR= 2CM, QS =?

Sum of given side = PQ + RS + PR

= 10CM + 10CM + 2CM = 22CM

Length of the four side = perimeter - sum of given side

= 24cm – 22cm

= 2cm

QS=2CM

 

          2.

 

 

 

 

In the figure, the measurements of four sides are given.

If the perimeter is 24cm, then find the length of remaining side.

 

Perimeter=24cm

AE= 3CM, EB= 4CM, CD= 8CM, AC= 4CM, BD=?

Sum of all side = AE + EB + CD + AC

= 3CM + 4CM + 8CM + 4CM = 19CM

Length of the five side = perimeter -sum of all sides

= 24cm - 19cm = 5cm

BD = 5CM.

 

 

              3.        

 

 

 

 

 

In the figure the length of one side is 7cm. if all the side

 are equal, then find its perimeter.

Perimeter = 7cm + 7cm + 7cm + 7cm

=28cm

KLMN = 28CM.

 

 

The space or the region bound by a given closed figure is called its area.

In general area is expressed in square unit.

Exercise 1.3

                   I            On the graph sheet given, the area of each square is

              1 sq cm. Find the area of the given shapes.

1.   

  

 

 

 

 

 Totally there are 5 squares.

     Area of given shape = 5 sq cm

 

2.      

Totally there are 21 squares.

Area of given shape = 21 sq cm    

3.

 

 

 

 

 

 

Totally there are 20 squares.

Area of given shape = 20 sq cm

  

 

4.         

 

Totally there are 16squares.

Area of given shape = 16 sq cm

5.      

 

Totally there are 12 squares.

Area of given shape = 12 sq cm