如图,在五边形ABCDE中,∠A+∠B+∠E=∠EDC+∠BCD+140°,DF,CF分别平分∠EDC和∠BCD,则∠F的度数为( )
A:100°
B:90°
C:80°
D:70°
如图,矩形ABCD中,点E在边AB上,将矩形ABCD沿直线DE折叠,点A恰好落在边BC的点F处.若AE=5,BF=3,则CD的长是( )