Question

two cubes of volume 64cm cube are join end to end together to get find the surface area of resulting cuboid

Answer 1

hello users ...
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we have given that :
two cubes are joined end to end to form a cuboid .
and
volume of cube = 64 cm³

we have to find :
surface area of cuboid = ? 

solution:-
we know that ;
volume of cube = a³
and 
surface area of cuboid = 2 [ lb + bh + hl ]

where l is the length , b is the breadth ,and h is the height of cuboid.

now,
According to the given ,
volume of cube = 64 cm³

=> a³ = 64 cm³

=> a =4 cm 

now , 
the cuboid is formed by end to end joining of two cubes 

=> length of cuboid = sum of length of two cubes
= a + a = 2a 
= 2 * 4 = 8 cm 
and 
breadth of cuboid = breadth of cube = a  = 4 cm 
and 
height of cuboi+d = height of cube = a = 4 cm 

Now,
surface area of cuboid = 2 [lb + bh + hl ]

= 2 *[ 8 * 4 + 4 * 4 + 4 * 8 ]

= 2 * [ 32 + 16 + 32 ]

= 2 * [ 80 ]

= 160 cm² Answer 
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@ hope it helps :)

Answer 2

Originally each side was 4 cm and now the length of the resulting cuboid is 8 cm and the breadth remains 4 cm and the height also remains 4 cm. Therefore, area of the cuboid is 2(lb + bh + hl) = 2( 32 + 16 + 32) = 2(80) = 160 sq.cms.