Cumulation

Cumulation is the dual operation of truncation which replaces the faces of a polyhedron with pyramids of height (where may be positive, zero, or negative) having the face as the base. relation between height and ratio of unit that folding ==>rt(4(a^2+1)^2-sec^2alpha(4a^4-4a^2+3))/4(a^2-1) a->0，alpha+->h+, a->1，alpha+->h- 但係我個conjucture係 a->0，h+(geometric+)，alpha+，h-(trigonometric-)，又冇計錯！