∵AB=BC=AC，∴∠A=∠B=∠C=60°，∵DE⊥AB，DF⊥AC，∴∠BDE=∠FDC=30°，∴BE=12BD，CF=12CD，∴BE+CF=12（BD+CD）=12BC，∴BE+CF+BC=32BC，AE+AF=3BC−32BC=32BC，∴AE+AF+EF=BE+CF+BC+EF，∴△AEF和四边形EBCF的...