题目

阅读理解What if we had the power tocontrol time, instead of moving from the past to the present to the future? Whatif we could jump, loop and travel through time in a machine? What if we could gowherever and whenever we pleased?This ability would allow usto witness historic wonders, change decisions and see people from the past. We couldright wrongs and stop wars from starting.The mysterious puzzle of timehas kept people debating its nature for hundreds of years. Science fiction writershave turned it into imaginative stories. Some scientists have even attempted toexplain it using math. Thi如图,两座建筑物的底部都在同一个水平面上,且均与水平面垂直,它们的高度分别是9和15,从建筑物的顶部看建筑物的视角. (1) 求的长度; (2) 在线段上取一点点与点不重合),从点看这两座建筑物的视角分别为问点在何处时,最小?