解:?$(1)$?過點?$P {作}PG//AB$?
∴?$∠BEP=∠EPG=36°$?
∵?$AB//CD,$?∴?$GP//CD$?
∴?$∠FPG=180°-∠CFP=28°,$?∴?$∠EPF=∠EPG+∠FPG=64°$?
?$(2)∠PF_{C}=∠PEA+∠P,$?理由:
如圖?$2,$?過?$P $?點作?$PN//AB,$?則?$PN//CD$?
∴?$∠PEA=∠NPE$?
∵?$∠FPN=∠NPE+∠FPE,$?∴?$∠FPN=∠PEA+∠FPE$?
∵?$PN//CD,$?∴?$∠FPN=∠PF C$?
∴?$∠PF C=∠PEA+∠FPE,$?即?$∠PF C=∠PEA+∠P$?
?$(3)$?如圖,過點?$G {作}AB$?的平行線?$GH$?
∵?$GH//AB,$??$AB//CD,$?∴?$GH//AB//CD$?
∴?$∠HGE=∠AEG,$??$∠HGF=∠CFG$?
又∵?$∠PEA$?的平分線和?$∠PF C$?的平分線交于點?$G$?
∴?$∠HGE=∠AEG=\frac 12∠AEP,$??$∠HGF=∠CFG=\frac 12∠CFP$?
由?$(1)$?可知,?$∠CFP=∠P+∠AEP$?
∴?$∠HGF=\frac 12(∠P+∠AEP)=\frac 12(α+∠AEP)$?
∴?$∠EGF=∠HGF-∠HGE=\frac 12(α+∠AEP)$?
?$=\frac 12α+\frac 12∠AEP-∠HGE=\frac 12α$?