题目

What makes you cry? Being moved by a sad movie, waving a loved one off, or getting emotional after splitting up with your partner can all cause tears to roll down our faces. We all have the power to cry, but is that a good thing?When you think about it, shedding(流) tears from your eyes is a strange thing to do. But it seems to be an automatic(无意识的) reaction when we get sad, upset or even when we're very happy. What causes this reaction differs from person to person. However, the feeling is the same ——your cheeks puff up(鼓起), your eyes tighten and before you know it, tears are如图，已知正方形ABCD和矩形ACEF所在的平面互相垂直，，AF=1．（1）求直线DF与平面ACEF所成角的正弦值；（2）在线段AC上找一点P，使与所成的角为60°，试确定点P的位置．