3.
如用,Rt△ABC中,AB⊥AC,AD⊥BC,BE平分∠ABC,交AD于E,EF∥AC,下列结论中:①AB=BF;②AE=ED;③AD=DC;④∠ABE=∠DFE;⑤$\frac{AB}{BD}$=$\frac{CF}{DF}$,正确的是( )
| A. | ①③ | B. | ①⑤ | C. | ③④ | D. | ①②⑤ |
1.
如图,矩形ABCD的面积为16cm2,对交线交于点O;以AB、AO为邻边作平行四边AOC1B,对角线交于点O1,以AB、AO1为邻边作平行四边形AO1C2B,…;依此类推,则平行四边形AO4C5B的面积为( )
0 282642 282650 282656 282660 282666 282668 282672 282678 282680 282686 282692 282696 282698 282702 282708 282710 282716 282720 282722 282726 282728 282732 282734 282736 282737 282738 282740 282741 282742 282744 282746 282750 282752 282756 282758 282762 282768 282770 282776 282780 282782 282786 282792 282798 282800 282806 282810 282812 282818 282822 282828 282836 366461
| A. | $\frac{1}{2}$cm2 | B. | 1cm2 | C. | 2cm2 | D. | 4cm2 |