在△ABC中，已知，c=2，B=30°，则b=（）．
A．1
B．2
C．3
D．4
参考答案：A
解析：
由余弦定理有故选A．
, the forest fire would have been discovered much earlier.
A．But for their care
B．Had they been more careful
C．Without their care
D．If they were careful
在Excel中，文本运算符“＆”可以将______文本连接为一个组合文本。
A．一个或多个 B．两个 C．至少三个 D．最多在三个
，c=2，B=30°，则b=（）．
有
故选A．
，c=2，B=30°，则b=（）．有故选A．