Question

The height of rectangular room is 1 m and its perimeter of the floor is 20 m find its area of four walls .​

Answer 1

perimeter = 2(l+b)

20 = 2(1+b)

1+b = 10

b = 9

area = lb

,= 1×9 = 9 m²

hope it's helpful you

Answer 2

$Heya\:$

=> Perimeter of rectangle=2(l+b)

height is 20m.

=> Now the formula used for finding surface are of walls is 2h(1+b)

Here you can clearly see there is 2(l+b) when you remove h.so the procedure is as follows

=> Perimeter=2(l+b)

= 20 m(already given)

=> height=1m(also given)

therefore,

2h(l+b)

or can be written as 2(l+b)h

which is 20 ×1 m

=20m square

◾Area of four walls =perimeter of base × height

A=wl

P=2(l+w)

Solving forA

A=Pl

2﹣l2 = 20·1

2﹣12 = 9m²

therefore the area of wall of room is

${9}m^{2}$