In this question we have to find edges of the three cubes having cubes of a metal whose edges are in the ratio 3: 4: 5 are melted and converted into a single cube whose diagonal is 12√3 cm.
This question is from r d sharma class 10 maths.
I found this question while doing maths class 10. I need help in getting the solution.
Let the edges of three cubes (in cm) be 3x, 4x and 5x respectively.
So, the volume of the cube after melting will be = (3x)3 + (4x)3 + (5x)3
= 9×3 + 64×3 + 125×3 = 216×3
Now, let a be the edge of the new cube so formed after melting
Then we have,
a3 = 216×3
a = 6x
We know that,
Diagonal of the cube = √(a2 + a2 + a2) = a√3
So, 12√3 = a√3
a = 12 cm
x = 12/6 = 2
Thus, the edges of the three cubes are 6 cm, 8 cm and 10 cm respectively.