13.
如图,AB∥CD,∠A=45°,∠C=28°,则∠AEC的大小为( )
| A. | 17° | B. | 28° | C. | 45° | D. | 73° |
11.
如图,正三角形ABC是⊙O的内接三角形,点P是劣弧AB上不同于点A、B的任意一点,则∠BPC的度数是( )
| A. | 30° | B. | 45° | C. | 50° | D. | 60° |
8.
如图,在边长为4的菱形ABCD中,∠BAD=120°,则对角线AC的长为( )
| A. | 4 | B. | 2 | C. | 2$\sqrt{3}$ | D. | 3 |
7.下列图形都是由同样大小的五角星按一定的规律组成,其中第①个图形一共有2个五角星,第②个图形一共 8个五角星,第③个图形一共有18个五角星,…,则第⑥个图形中五角星的个数为( )

| A. | 50 | B. | 64 | C. | 68 | D. | 72 |
6.关于x的方程(m-1)x2+2x+1=0有实数根,则m的取值范围是( )
0 284684 284692 284698 284702 284708 284710 284714 284720 284722 284728 284734 284738 284740 284744 284750 284752 284758 284762 284764 284768 284770 284774 284776 284778 284779 284780 284782 284783 284784 284786 284788 284792 284794 284798 284800 284804 284810 284812 284818 284822 284824 284828 284834 284840 284842 284848 284852 284854 284860 284864 284870 284878 366461
| A. | m≤2 | B. | m<2 | C. | m<3且m≠2 | D. | m≤3且m≠2 |