Frustum of a right circular cone is that portion of right circular cone included between the base and a section parallel to the base not passing through the vertex.
Frustum of a pyramid (or cone) is a portion of pyramid (or cone) included between the base and the section parallel to the base not passing through the vertex.
Cone
The surface generated by a moving straight line (generator) which always passes through a fixed point (vertex) and always intersects a fixed plane curve (directrix) is called conical surface. Cone is a solid bounded by a conical surface whose directrix is a closed curve, and a plane which cuts all the elements. The conical surface is the lateral area of the cone and the plane which cuts all the elements is the base of the cone.
Problem 668
For the beam shown in Fig. P-668, compute the value of P that will cause the tangent to the elastic curve over support R2 to be horizontal. What will then be the value of EIδ under the 100-lb load?