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If the volume of a cube is 512 cm3, then the measure of the main diagonal of the cube will be:
173 cm
143 cm
73 cm
83 cm
83 cm
Memorize common perfect cubes like 83=512. Once the side a=8 is found, the diagonal is simply a3.
Volume of the cube V = 512 cm³
V=a3, d=a3
Memorize common perfect cubes like 83=512. Once the side a=8 is found, the diagonal is simply a3.
Students often mistake the formula for the diagonal of a square (face diagonal, a2) instead of the main diagonal of a cube (a3).
Calculate the side length
Given the volume of the cube V=a3=512, take the cube root to find the side length a.
a=3512=8 cm
Calculate the main diagonal
The formula for the main diagonal d of a cube with side length a is d=a3. Substitute a=8 into the formula.
d=83 cm
D is correct because the side of the cube is 3512=8 cm, making the main diagonal 83 cm.
This concept is frequently tested alongside lateral surface area (4a2) and total surface area (6a2) of a cube in various competitive exams.