题目

Languages are important. But how they appeared is largely mystery（谜）. It is interesting to see how deaf people can create novel sign languages immediately. Observations have shown that when deaf strangers are brought together in a community, they come up with their own sign language in a considerably short amount of time. However, how exactly this happened has not been recorded, as Manuel Bohn describes, “We know relatively little about how social interaction becomes language. This is where our new study comes in.”In a series of studies, researchers attempted to recreate exactly this在△ABC中，，．（Ⅰ）求sinA的值；（Ⅱ）设，求△ABC的面积．