∵DE是AB边上的垂直平分线,∴AE=BE,∵AB=8cm,△BCE的周长是14cm,∴AC=8cm,BC+BE+EC=BC+AE+EC=BC+AC=14(cm),∴BC=6cm;设∠ABE=2x°,∠EBC=x°,∵AE=BE,∴∠A=∠ABE=2x°,∵AB=AC,∴∠C=∠ABC=∠ABE+∠EBC=3x°,∵∠ABC+∠A+∠C=180°,∴3x+2x+3x=180,解得:x=22.5°,∴∠A=45°.故答案为:6cm,45°.