17.
如图,已知直线AB、CD相交于点O,OA平分∠EOC,∠EOD=110°,则∠BOD=( )
| A. | 30° | B. | 35° | C. | 20° | D. | 40° |
15.在Rt△ABC中,∠C=90°,a=12,b=5,则c的长为( )
| A. | 13 | B. | 14 | C. | 15 | D. | 16 |
14.若$\sqrt{{x^2}-6x+9}$=3-x,则x的取值范围是( )
| A. | x为任意实数 | B. | x≥3 | C. | x>3 | D. | x≤3 |
11.一元一次方程$\frac{2x+1}{3}$-$\frac{x-3}{6}$=1,去分母后得( )
| A. | 2(2x+1)-x-3=1 | B. | 2(2x+1)-x-3=6 | C. | 2(2x+1)-(x-3)=1 | D. | 2(2x+1)-(x-3)=6 |
10.
如图,四边形ABCD是⊙O的内接四边形,若∠B=80°,则∠ADC的度数是( )
| A. | 60° | B. | 80° | C. | 90° | D. | 100° |
9.
如图,在平面直角坐标系中,四边形OABC是边长为1的正方形,顶点A、C分别在x轴的负半轴、y轴的正半轴上.若直线y=kx+2与边AB有公共点,则k的值可能为( )
| A. | $\frac{1}{2}$ | B. | $\frac{3}{2}$ | C. | $\frac{5}{2}$ | D. | 3 |
8.
设a、b为常数,且b>0,抛物线y=ax2+bx+a2-5a-6为下列图形之一,则a的值为( )
0 284781 284789 284795 284799 284805 284807 284811 284817 284819 284825 284831 284835 284837 284841 284847 284849 284855 284859 284861 284865 284867 284871 284873 284875 284876 284877 284879 284880 284881 284883 284885 284889 284891 284895 284897 284901 284907 284909 284915 284919 284921 284925 284931 284937 284939 284945 284949 284951 284957 284961 284967 284975 366461
| A. | 6或-1 | B. | -6或 1 | C. | 6 | D. | -1 |