2Pmk1cosktiswellknowninthestudyofFourierseriessee3astheDirichletkernelThisfunctionisusedintheproofofDirichletstheoremwhichimpliesthatifafunctionftiscontinuousonandhasffthe ID: 332045
2+Pmk=1cos(kt)iswell-knowninthestudyofFourierseries(see[3])astheDirichletkernel.ThisfunctionisusedintheproofofDirichlet'stheorem