Question

Not let's try this in 3-D. Calculate r and a relationship from the following figure.

If $a=x\ast r$, type x.

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Answer 1

From the figure we notice that the spheres are touching each other and the faces of the cube. The centers of the spheres are in a straight line.

So, we can infer that the side of the cube is equal to the sum of the diameters of the 2 spheres.

That means, a = 2d

⇒ a = 4r

⇒ x = 4