12.在△ABC中,O为中线AM上一个动点,若AM=4,则((OA×(((OB+((OC)的最小值是__________.
11.若在上是单调函数,则的取值范围是__________.
10.在△ABC中,BC=1,,当△ABC的面积等于时,__________.
9.函数为增函数的区间是__________.
8.已知向量满足,则的夹角为__________.
7.若复数z满足|z| - = ,则z =__________.
6.已知,则__________.
5.已知向量,若,则=__________.
4.在中,,则的值为__________.
3.若是纯虚数,则实数的值是__________.