假设AD长为X,在正方形ABCD内,AE⊥AF,tan∠DAF=1/3所以∠1=∠3,所以ΔAEB和ΔADF全等,所以AE=ADSΔAEF=1/2(AE)X(AF)=5乘以X的平方=10当tan∠DAF=2/3时,SΔAEF=1/2(AE)X(AF)=13
