If the bottom diameter of a circle is 25 what would the diameter be if the circle was built up into a sphere? Or in other words, extended into a full sphere with the bottom layer remaining 25 (I'm trying to make a top to my tower on minecraft ^^; )

Question

phi · Answer

I can only guess what you are asking....

You could make the top sphere as big as you like.  But if you want a hemisphere (like the top of a silo), you could chose the same diameter 25.  This gives a radius of 12.5, which will be the additional height of the (half) sphere on top of the tower

I am thinking this is what you have:
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