如图在三棱柱ABC-A1B1C1中，设∠AA1B1=∠AA1C1=60°，由条件有∠C1A1B1=60°，作AO⊥面A1B1C1于点O，
则 cos∠AA1O=
| cos∠AA1B1 |
| cos∠B1A1O |
| cos600 |
| cos300 |
| 1 | ||
|
| ||
| 3 |
∴sin∠AA1O=
| ||
| 3 |
∴AO=AA1•sin∠AA1O=
2
| ||
| 3 |
∴VABC-A1B1AOC1=S△A1B1C1•AO=
| 1 |
| 2 |
2
| ||
| 3 |
| 2 |
故选B．
如图在三棱柱ABC-A1B1C1中，设∠AA1B1=∠AA1C1=60°，| cos∠AA1B1 |
| cos∠B1A1O |
| cos600 |
| cos300 |
| 1 | ||
|
| ||
| 3 |
| ||
| 3 |
2
| ||
| 3 |
| 1 |
| 2 |
2
| ||
| 3 |
| 2 |