6.
如图,?ABCD的对角线AC、BD相交于点O,增加下列条件后,?ABCD不一定是菱形的是( )
| A. | DC=BC | B. | AC⊥BD | C. | AB=BD | D. | ∠ADB=∠CDB |
3.
如图,在矩形ABCD中,AB=$\sqrt{3}$,AD=1,把该矩形绕点A顺时针旋转α度得矩形AB′C′D′,点C′落在AB的延长线上,则图中阴影部分的面积是( )
0 282588 282596 282602 282606 282612 282614 282618 282624 282626 282632 282638 282642 282644 282648 282654 282656 282662 282666 282668 282672 282674 282678 282680 282682 282683 282684 282686 282687 282688 282690 282692 282696 282698 282702 282704 282708 282714 282716 282722 282726 282728 282732 282738 282744 282746 282752 282756 282758 282764 282768 282774 282782 366461
| A. | $\frac{\sqrt{3}}{2}$$-\frac{π}{4}$ | B. | $\frac{\sqrt{3}}{2}-\frac{π}{12}$ | C. | $\frac{\sqrt{3}}{2}-\frac{π}{2}$ | D. | $\frac{\sqrt{3}}{2}-\frac{π}{6}$ |