Answer:
Well polygenetic inheritiance are traits that is controlled by multiple genes, so for one trait you may have more than two gene controlling it, human eye is an example. For polygenetic inheritance you cannot do a pedigree and calculated the percentage. For mendelian inheritance it all about two alleles for one trait where one is definetly more dominant over the other, it is much simpler than the polygenic trait and can be calculated through a pedigree.