Question

Exercise 4 (C)
1. Find the area of rectangle whose length and breadth
are
(a) length = 16 cm breadth = 12 cm
(b) length = 9 cm breadth = 8 cm
(c) length = 25 cm breadth = 16 cm
(d) length = 11,2 m breadth = 9 m.​

Answer 1

Answer:

It is given that,

Length of a rectangle = 25 cm.

Breadth of a rectangle = 16 cm.

We know that,

Area of a rectangle = l∗b

Substituting the values,

=25∗16

=400cm2.

Answer 2

SOLUTION

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large length(l)}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large breadth(b)}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

$\boxed{ \sf Area\ of \ a \ rectangle = length * breadth\: ( l *b) }$

Area of Rectangle whose length and breadth are :-

(a) length = 16 cm breadth = 12 cm

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large 16 cm}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large 12 cm}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

Area of the rectangle = length × breadth

                                  = 16 × 12 = 192 cm²

(b) length = 9 cm breadth = 8 cm

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large 9 cm}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large 8cm}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

Area of the  rectangle = length × breadth

                                  = 9 × 8 = 72 cm²

(c) length = 25 cm breadth = 16 cm

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large 25 cm}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large 16cm}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

Area of the rectangle = length × breadth

                                = 25 × 16 = 400 cm²

(d) length = 11,2 m breadth = 9 m.​

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large 11.2m}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large 9m}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

Area of a rectangle = length × breadth

                                 = 11.2 × 9 = 100.8 m²

Formula for area  of Five Common Shapes

Rectangle

Area = length × breadth or l × b

Square

Area = Square of the sides or a²

Circle

Area = πr²

Triangle

$\sf Area = \dfrac{1}{2} \:base * height \:or\ \dfrac{1}{2} bh$

Parallelogram

Area = base × height or b×h