Sphere Volume.

[Dieter]

(03-31-2016 02:23 PM)ggauny@live.fr Wrote:  Of course I have see the answers, but me I find :

4/3(Pi*(D/2)^3)
8/6(3*Pi*(D/6)^3)
and if I divise all by 6 I obtain :

8(3*Pi*D^3)
so it is 24*Pi*D^3 and it is false !

You obviously forgot some basic math rules.

First of all, forget the brackets (except around d/2). All values are faktors, so there is no need to set brackets.

Then, (a/b)^n = a^n / b^n.
So...

   4/3 * pi * (d/2)^3
= 4/3 * pi * d^3 / 2^3
= 4/3 * pi * d^3 / 8
= 4/3/8 * pi * d^3
= 4/24 * pi * d^3
= pi * d^3 / 6

Dieter