Find Volume of a Wineglass - a Slice

A spherical wineglass, known diameter, is brim full of wine. What is the width of any vertical parallel slice with a volume of 1/4 of the wine?

Assume that the height of the wineglass is known.

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"Spherical wineglass".. how is it meant? can we assume it is a full sphere, or chopped? – Berci Oct 6 '12 at 8:44
Spherical wineglasses would be rather frustrating, methinks ... – Peter Smith Oct 6 '12 at 9:13
The wineglass is chopped – D Abbott Oct 6 '12 at 9:16
Perhaps you mean a hemispherical wineglass? – TonyK Oct 6 '12 at 10:43
What curve are you calling a wineglass? – Loki Clock Jun 6 '13 at 17:53

Use the disk (washer) method for the function $f(x):=\sqrt{R^2-x^2}$ on the interval $[x_0,x_0+h]\subset[-R,R]$ to get an equation satisfied by $x_0$ and $h$.