The ratio of the length of diagonal of two cubes is 2 ∶ 3 and the difference between the total surface area of the bigger cube and the lateral surface area of the smaller cube is 342 cm2. Find the total surface area of a statue which is formed by placing the smaller cube upon the bigger cube.
The ratio of the length of diagonal of two cubes is 2 ∶ 3 and the difference between the total surface area of the bigger cube and the lateral surface area of the smaller cube is 342 cm2. Find the total surface area of a statue which is formed by placing the smaller cube upon the bigger cube. Correct Answer 630 cm<sup>2</sup>
Calculation:
Since, diagonal ratio = side ratio of cube = 2 ∶ 3
Let the ratio be x
So, the side of the first cube = 2x
And the side of the second cube = 3x
According to question,
The total surface area of the bigger cube – Lateral surface area of smaller cube = 342
So, 6 (3x)2 – 4 (2x)2 = 342
⇒ 38x2 = 342
So, x = 3
So, the side of the smaller cube = 2 × 3 = 6
And the side of the bigger cube = 3 × 3 = 9
So, the area of statue = total surface area of bigger cube + total surface area of the smaller cube – 2 × areas of one face of the smaller cube
So, the required area = 6 × 92 + 6 × 62 – 2 × 62
Hence, 630 cm2