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19 votes
19 votes
A cube of side length s sits inside a sphere of radius r so that the vertices of the cube sit on the sphere. Find the ratio r : s

User Wetjosh
by
2.7k points

1 Answer

19 votes
19 votes

Answer:

r : s is √3 : 2

Explanation:

The given parameter are;

A cube is inscribed in a sphere

The side length of the cube = s

The radius of the sphere = r

The ratio r : e = Required

It is noted that for a cube inscribed in a sphere, we have;

The diameter of the sphere = The diagonal of the cube

The diameter of the sphere, D = 2 × The radius = 2·r

The square of the diagonal of the cube, d² = s² + s² + s² = 3·s²

∴ The diagonal of the cube, d = (√3)·s

From the relationship between the cube and the sphere in which it is inscribed, (The diameter of the sphere = The diagonal of the cube), we have;

2·r = (√3)·s

∴ r/s = (√3)/2

r : s = √3 : 2.

User Sachin Lala
by
3.1k points
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