National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Conical Sections
This question and answer site deals with finding the diameter of one end of a frustum of a cone when you know the diameter and angle of the end as well as the length of the cone.
Math Words
Math Words: Frustum of a Cone or Pyramid
This site defines a frustum and has links to related topics. The site offers the formula for the lateral area, volume, and total surface area of frustum of a cone.
National Council of Teachers of Mathematics
The Math Forum: Volume and Surface Area of a Cone Frustum
This question and answer site deals with the derivation of the formula for the surface area for the frustum of a right circular cone.