[it's a cone with a smaller cone chopped off]
[it's a part of an annulus]
what if you don't know 'h' ?
find the volume of the cup
what is the volume of this bowl?
work out the dimensions of the portion of the annulus (washer shape) needed to make the fabric of this lampshade
(ignoring any overlap of material)
show that the angle required is 207.57 (to 2dp) degrees