# Questions tagged [spheres]

For geometrical problems involving spheres. Use the tag (geometry) as well. For intrinsic geometry of spheres, see (spherical-geometry).

813 questions
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### Radius of a Cylinder ($r$) and Radius of a Sphere ($R$)

The Image What would $R$ (the radius of the sphere) be in accordance with the radius of a cylinder? The cylinder had $r$ as is radius and $r/6$ as its height. The sphere just had $R$ as its radius ...
1answer
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### radius of the inscribed sphere of the pyramid in $\mathbb{R^5}$

How to find the radius of the inscribed sphere of the pyramid in $\mathbb{R^5}$ with the vertex in $(1,0,0,0,0)$, which base is a regular $4$-dimensional simplex, luying in the hyperplane $x_1=0$ with ...
2answers
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### Field of view angle taken up by a sphere of a certain radius at a certain disance [on hold]

Is tan(radius/distance) the correct way to work out the angle of the two grey lines in this diagram? Thanks for the help.
1answer
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1answer
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### Surface area of a sphere dilemma

I recently found that surface area of a sphere can't be found with the following method. What's the flaw in it? First, I have taken a very thin ring of thickness $dx$ at a distance of $x$ from the ...
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5answers
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### 4 Spheres all touching each other??

If there are 4 spheres all touching each other and 3 of them have diameters 4, 6 and 12 what is the diameter of the fourth one? I imagine it like 3 balls on a flat table touching each other and then ...
1answer
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### How to calculate the geometric center of the surface-area of a part of a Sphere?

I have a regular sphere, $V=\pi r^3\frac4 3$ and $A=4\pi r^2$. Now I want to seperate it into four slices, with equal amounts of surface area - not counting the sliced area. Or in other words, I want ...
0answers
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### Surface area of a sphere segment. [duplicate]

I got this problem and solution in a paper but cannot find how they have solved it. Consider I have a sphere that is equally divided into two different patch(P, S). The sphere can rotate and translate(...
1answer
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### Area of touching part of Sphere to the wall.

I believe that it has a very simple explanation but one question stuck in my mind. What is the area between sphere and wall when it touches to it. If it is zero, why it is not occurring in real life?...