如图,已知AB=6,AC=7,BO、CO分别是∠ABC和∠ACB的角平分线,EF经过点O且EF∥BC,则△AEF的周长是
如图所示,在△ABC中,AB=AC,BD是角平分线,若∠BDC=69°,则∠A=
如图,在△ABA1中,∠B=20°,∠BAA1=∠BA1A,在A1B上取一点C,延长AA1到A2,使得∠A1CA2=∠A1A2C;在A2C上取一点D,延长A1A2到A5,使得∠A2DA3=∠A2A3D,…,按此做法进行下去,∠An的度数为| 80° |
| 2n-1 |
| 80° |
| 2n-1 |
如图,在△ABC中,AB=AC,D为BC边上一点,且∠BAD=30°,若AD=DE,∠EDC=33°,则∠DAE的度数为