已知四边形ABCD是菱形,△AEF是正三角形,E、F分别在BC、CD上,且EF=CD,则∠BAD=_度.
问题描述:
已知四边形ABCD是菱形,△AEF是正三角形,E、F分别在BC、CD上,且EF=CD,则∠BAD=______度.
答
设∠BAE=x,∵AE=AF=EF=CD,∠B=∠D,∴∠B=∠D=∠AEB=∠AFD,∴△ABE≌△ADF∴∠BAE=∠DAF=x,∵BC∥AD∴∠AEB=∠EAD∴∠ABC=∠AEB=∠EAF+∠DAF=60°+x,∵∠ABC+∠AEB+∠BAE=180°,∴60°+x+60°+x+x=180°,∴x=...