题目

如图，在直四棱柱中，四边形为平行四边形，，直线与平面所成角的正弦值为.（1）求点到平面的距离；（2）求平面与平面的夹角的余弦值. 答案：【答案】（1）；（2）.【解析】（1）由条件可得，然后建立空间直角坐标系，设，算出平面的法向量，然后由条件可求出，然后可算出答案；（2）算出平面的法向量，然后可算出答案.（1）因为，所以，所以如图建立空间直角坐标系，设，则设平面的法向量为则，即，所以可取所以，解得所以，所以点单词拼写。结合语境，根据首字母提示用单词的适当形式填空。【1】 I know that too much f______ leads to heart attack and high blood pressure, so I seldom eat meat.【2】Do not give the baby meat to eat, because it is not easily d______.【3】Good health depends on a b_________ diet, proper exercise and enough sleep.【4】Ride three to four times a week, you can let the body stay s_______.【5】Sports could give me a strong and e_________ body and a healthy life.