8.
如图,两个全等的矩形ABCD和GBEF,点A,B,E在同一条直线上,对角线AC和EG相交于点O.若点O恰好是EG的中点,BC=1,则AB的长是( )
| A. | $\sqrt{2}$ | B. | 2 | C. | $\sqrt{2}$+1 | D. | $\sqrt{2}$-1 |
5.
如图,已知直线l1∥l2,将等边三角形如图放置,若∠α=40°,则∠β等于( )
0 297115 297123 297129 297133 297139 297141 297145 297151 297153 297159 297165 297169 297171 297175 297181 297183 297189 297193 297195 297199 297201 297205 297207 297209 297210 297211 297213 297214 297215 297217 297219 297223 297225 297229 297231 297235 297241 297243 297249 297253 297255 297259 297265 297271 297273 297279 297283 297285 297291 297295 297301 297309 366461
| A. | 20° | B. | 30° | C. | 40° | D. | 50° |