4.
如图,折叠矩形纸片ABCD的一边AD,使点D落在BC边的点F处,已知AB=8 cm,BC=10 cm,则EC的长( )
| A. | 3 cm | B. | 4 cm | C. | 5 cm | D. | 6 cm |
3.关于x的不等式组$\left\{\begin{array}{l}x>a\\ x>2-a\end{array}\right.$的解集是x>a,则a的取值范围是( )
| A. | a>1 | B. | a≤1 | C. | a≥1 | D. | a<1 |
2.已知△ABC的三边分别为a,b,c,则下列条件中△ABC不是直角三角形的是( )
| A. | b2=a2-c2 | B. | ∠C=∠A-∠B | C. | ∠A:∠B:∠C=3:4:5 | D. | $a:b:c=3:4:\sqrt{7}$ |
1.若a<b,则下列不等式一定成立的是( )
| A. | $\frac{b}{a}$>1 | B. | $\frac{a}{b}$<1 | C. | -a>-b | D. | a-b>0 |
18.
如图所示,实数a、b在数轴上的位置,化简:$\sqrt{(a-b)^{2}}$-$\sqrt{{a}^{2}}$-$\sqrt{(b-1)^{2}}$=( )
0 294504 294512 294518 294522 294528 294530 294534 294540 294542 294548 294554 294558 294560 294564 294570 294572 294578 294582 294584 294588 294590 294594 294596 294598 294599 294600 294602 294603 294604 294606 294608 294612 294614 294618 294620 294624 294630 294632 294638 294642 294644 294648 294654 294660 294662 294668 294672 294674 294680 294684 294690 294698 366461
| A. | 2b-2a-1 | B. | -2a+1 | C. | 1 | D. | 2b-1 |