10.
在Rt△ABC中,∠C=90°,AB=5,BC=4,那么cosA为( )
| A. | $\frac{4}{5}$ | B. | $\frac{3}{5}$ | C. | $\frac{4}{3}$ | D. | $\frac{3}{4}$ |
9.
如图,AB为⊙O的直径,P点在AB延长线上,PM切⊙O于M点,若OA=a,PM=$\sqrt{3}$a,那么△PMB的周长为( )
| A. | 2a | B. | 2$\sqrt{3}$a | C. | a | D. | (2+$\sqrt{3}$)a |
8.若二次函数y=ax2+c的图象经过点P(1,3),则该图象必经过点( )
| A. | (1,-3) | B. | (-1,3) | C. | (3,-1) | D. | (-3,1) |
7.抛物线y=-$\frac{1}{2}$x2+1的顶点坐标是( )
| A. | (0,1) | B. | ($\frac{1}{2}$,1) | C. | (-$\frac{1}{2}$,-1) | D. | (2,-1) |
3.
如图,已知在平面直角坐标系xOy中,O为坐标原点,点P是反比例函数y=$\frac{6}{x}$(x>0)图象上的一个动点,若以点P为圆心,3为半径的圆与直线y=x相交,交点为A、B,当弦AB的长等于2$\sqrt{5}$时,点P的坐标为( )
| A. | (1,6)和(6,1) | B. | (2,3)和(3,2) | C. | ($\sqrt{2}$,3$\sqrt{2}$)和(3$\sqrt{2}$,$\sqrt{2}$) | D. | ($\sqrt{3}$,2$\sqrt{3}$)和(2$\sqrt{3}$,$\sqrt{3}$) |
2.
如图,已知抛物线y=x2+bx+c与直线y=x交于(1,1)和(3,3)两点,现有以下结论:①b2-4c>0;
②3b+c+6=0;
③当x2+bx+c>$\frac{2}{x}$时,x>2;
④当1<x<3时,x2+(b-1)x+c<0,
其中正确的序号是( )
0 288447 288455 288461 288465 288471 288473 288477 288483 288485 288491 288497 288501 288503 288507 288513 288515 288521 288525 288527 288531 288533 288537 288539 288541 288542 288543 288545 288546 288547 288549 288551 288555 288557 288561 288563 288567 288573 288575 288581 288585 288587 288591 288597 288603 288605 288611 288615 288617 288623 288627 288633 288641 366461
②3b+c+6=0;
③当x2+bx+c>$\frac{2}{x}$时,x>2;
④当1<x<3时,x2+(b-1)x+c<0,
其中正确的序号是( )
| A. | ①②④ | B. | ②③④ | C. | ②④ | D. | ③④ |