1) The study of isoperimeters 
• (n.) The science of figures having equal perimeters or boundaries.
I`so·per·im'e·try noun (Geom.) The science of figures having equal perimeters or boundaries. 
isoperimetry 1. That branch of geometry which deals with isoperimetrical figures, and the problems connected with them. 2. The science of figures having equal perimeters or boundaries.
the study of isoperimeters.