8.等腰△ABC中,AB=AC,BD是腰AC上的高线,∠DBC=15°,若BD=5,则AC等于( )
| A. | 5 | B. | 10 | C. | 2.5 | D. | 15 |
7.下列计算正确的是( )
0 278970 278978 278984 278988 278994 278996 279000 279006 279008 279014 279020 279024 279026 279030 279036 279038 279044 279048 279050 279054 279056 279060 279062 279064 279065 279066 279068 279069 279070 279072 279074 279078 279080 279084 279086 279090 279096 279098 279104 279108 279110 279114 279120 279126 279128 279134 279138 279140 279146 279150 279156 279164 366461
| A. | (-2a3)3=-8a6 | B. | m6÷m2=m3 | ||
| C. | x2008+x2008=2x2008 | D. | t2•t3=t6 |