[?] Plot disks of radius r=1-f[x]?

Questions
1

Hi i’m trying to plot disks of radius =(1-f[x]), so that it makes a sphere, as we know that the volume of a cylinder having height=2 radius - the volume of the cone having radius r, is always equal to the volume of a sphere having radius r. but i want to show that using disks.

2

V = Manipulate[
h[x_] := x;
a = 0;
b = 1;
startpos[k_] := a + (k - 1) 0.01;
a1 = Plot[{1, -1, t, -t}, {t, 0, 1}, AspectRatio → Automatic,
ImageSize → Medium];
b = Graphics[
Table[{Red, Opacity[0.5], Disk[{x, 0}, {0.01, 2}], Green,
EdgeForm[Black], Disk[{x, 0}, {0.01, h}]}, {x, 0, r, 0.1}],
AspectRatio → Automatic, ImageSize → Medium];
aa = Table[
Graphics3D[{{Opacity[2/5],
Cylinder[{{-1, 0, 0}, {1, 0, 0}}, 1]}, {Opacity[1/5],
Cylinder[{{i, 0, 0}, {i + 0.02, 0, 0}}, i]}}, Boxed → False,
AspectRatio → Automatic, ImageSize → Medium, FaceGrids → All,
ViewPoint → Front], {i, 0, r, 0.1}];
{Show[a1, b], Show[aa]}
, {r, 0, 1}]