1.人一根头发的直径大约为0.000072米,用科学记数法表示正确的是( )
| A. | -7.2×105 | B. | -7.2×104 | C. | 7.2×10-4 | D. | 7.2×10-5 |
17.估计与$\sqrt{11}$最接近的整数是( )
| A. | 3 | B. | 4 | C. | -3 | D. | ±3 |
16.下列计算正确的是( )
| A. | $\sqrt{3}$+$\sqrt{2}$=$\sqrt{5}$ | B. | $\sqrt{12}$÷$\sqrt{3}$=2 | C. | $\sqrt{6}$×(-$\sqrt{3}$)=3$\sqrt{2}$ | D. | ($\sqrt{3}$-1)2=2 |
12.
如图,△ABC外角∠CBD,∠BCE的平分线BF、CF相交于点F,则下列结论成立的是( )
0 282086 282094 282100 282104 282110 282112 282116 282122 282124 282130 282136 282140 282142 282146 282152 282154 282160 282164 282166 282170 282172 282176 282178 282180 282181 282182 282184 282185 282186 282188 282190 282194 282196 282200 282202 282206 282212 282214 282220 282224 282226 282230 282236 282242 282244 282250 282254 282256 282262 282266 282272 282280 366461
| A. | AF平分BC | B. | AF⊥BC | C. | AF平分∠BAC | D. | AF平分∠BFC |