Question

the perimeter of the floor of a room is 40m and its height is 4.5m find the area of four walls of the room

Answer 1

We are given  perimeter of floor = 40 m
We know that floor is in the shape of rectangle

so, 2(l+b) = 40
    so, (l+b) = 20 m  ................................................................(1)
        
         we also have, height, h = 4.5 m
 So, Area of four walls = 2(l+b)h
                                       = 2(l+b)*4.5
                                       = 2(20)*4.5                        [By Eqn (1)]
                                       = 20*9
                                       = 180 m²

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