16.方程组$\left\{\begin{array}{l}{x-y=1}\\{2x+y=5}\end{array}\right.$的解是( )
| A. | $\left\{\begin{array}{l}{x=2}\\{y=-1}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=-1}\\{y=2}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=1}\\{y=2}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$ |
8.
如图,A、B两点均在由小正方形组成的网格格点上,若C点也在格点上,且△ABC是等腰直角三角形,则符合条件的C点的个数有( )
| A. | 3个 | B. | 4个 | C. | 5个 | D. | 6个 |
7.已知圆锥底面半径为2,母线长为5,则此圆锥侧面展开图的面积是( )
0 284524 284532 284538 284542 284548 284550 284554 284560 284562 284568 284574 284578 284580 284584 284590 284592 284598 284602 284604 284608 284610 284614 284616 284618 284619 284620 284622 284623 284624 284626 284628 284632 284634 284638 284640 284644 284650 284652 284658 284662 284664 284668 284674 284680 284682 284688 284692 284694 284700 284704 284710 284718 366461
| A. | 5π | B. | 10π | C. | 7π | D. | 20π |